Tesi sul tema "Beer flavour"

One of the most important contributions to flavour compounds in beer is that associated with the activity of yeast. A kinetic model that quantitatively predicts the influence of changing process parameters on yeast metabolism and the production of flavour compounds would be invaluable. However a review of the literature has revealed that there is an absence of good quantitative data on which to build a model. The literature uses a wide variety of yeast strains and undefined fermentation media. There is also very little quantitative analysis of flavour formation and the models that have been published have little physiological relevance. The aim of the present study was to develop a kinetic model that would describe the production of the higher alcohols, isoamylalcohol and isobutanol, by the yeast N.C.Y.C 1681 within a brewery fermentation system. H.P.L.C., G.C. and enzyme assay analytical methods were developed that allowed the determination of concentrations of pertinent medium components during a fermentation. Amino acid concentrations were determined using Pico-tag (P.I.T.C.) pre-column derivatisation chemistry. Beer volatile components were analysed using G.C. head space analytical procedures. Yeast growth was studied in experimental defined media and in the complex wort medium. The vessels of the study were stirred tank fermenters, tall tubes and brewery cylindroconicals. Higher alcohol production is intimately linked with the yeast populations amino acid metabolism. Thus the influence of medium nitrogen content was investigated in relation to catabolic and anabolic production of higher alcohols.

A preliminary trial to determine the effect of repeated freezing and thawing on beef striploins, showed that the effect of thawing on frozen non-aged beef significantly improved tenderness, flavour and acceptability, indicating that thawing had a similar effect to aging. In the subsequent study, 207 beef striploins were collected from the Southern Crossbreeding Project (SXB: 70 heifers grainfed for 80 days, 70 steers grainfed for 180 days), Davies Gene Mapping Project (DGM: 30 steers grainfed for 180 days) and also 37 Hanwoo striploins imported into Australia from Korea. SXB animals consisted of Hereford cross calves sired by Belgian Blue, Limousin, South Devon, Hereford, Angus, Wagyu and Jersey bulls. DGM animals consisted of purebred Limousins and Jerseys and Limousin by Jersey crosses. Sensory analysis of beef striploins involved semi-trained taste panel assessments, using nine-point category scales for initial and sustained juiciness, beef flavour, beef fat flavour, oily flavour, buttery flavour, chicken-skin flavour, corn flavour, grassy flavour and overall acceptability. Flavour acceptability was positively enhanced by increased levels of intramuscular fat (IMF%). Significant differences in breed were apparent for juiciness, beef flavour, buttery flavour and flavour acceptability, after adjusting data to a constant level of intramuscular fat, suggesting that some variation in flavour may be genetic. The Korean Hanwoo displayed a numerically higher intensity of chicken score and lower intensity of beef flavour. Australian cattle breeds differed in fatty acid composition between each other and also to that of the Korean Hanwoo. The latter had 57% mono-unsaturated fatty acids, which was significantly higher (P<0.001) than the Australian breeds (47%). Since IMF% was confounded with breed, breed differences were not significant when adjusted for IMF%. Jersey animals most closely resembled the Hanwoo in fatty acid profile, whilst animals containing Limousin differed markedly from the Hanwoo. A chemical sensor was able to establish significant differences between Korean Hanwoo and Australian animals and predominantly mirrored differences in fatty acid composition and to some extent flavour. Development of prediction equations from individual fatty acids was disappointing (R2< 15%). However, when fatty acid data, IMF% and chemical sensor data were combined to form prediction equations, moderate R2 values were obtained of (24% to 43%).
Thesis (M.Ag.Sc.)--School of Agriculture & Wine, 2001.

Beer, as manufactured, is not at chemical equilibrium and undergoes complex chemical reactions during storage which can lead to undesirable changes in the sensory characteristics of beer. Since beer contains more than 600 volatile compounds, beer flavour change is a complex field of research and the dependable prediction of shelf life remains a top research priority. Chapter 1 places the work described in this thesis into this context. Chapters 2 and 3 provide details of the experimental methods used and their development, respectively, to evaluate flavour stability. The methods used and developed include: (i) the determination of one of the major antioxidants present in beer, sulphur dioxide (SO2), via distillation; (ii) a solid phase micro extraction (SPME)-GC-MS method with on fibre derivatization as a reliable detection method for aldehydes related to off flavours perceived in aged beer; (iii) measurement of the oxidative stability using electron paramagnetic resonance (EPR) spectroscopy. Chapter 4 describes oxidative stability measurements via EPR spectroscopy for three different lager-style beer qualities pre- and post-filtration. The trial included a large scale Kieselguhr frame filter, and two pilot-scale membrane filtration system. The results illustrate how EPR spectroscopy is sensitive to metal ion pick-up from traditional filter media and oxidative stability measures were evaluated versus oxygen pick up during filtration and sulphur dioxide content of the beer samples. The effect of a brewhouse addition of gallotannins on the flavour stability of a lager-style beer was investigated in Chapter 5. Pilot scale (16 hl) and large scale production line (1500 hl) experiments with gallotannins additions in the Brewhouse were performed. The effects of the different additions were monitored at key points of the production process and through to the final beer. Despite showing significant improvements in the pilot scale wort samples, the results for the related packed beer samples did not show clear flavour stability improvements. For the production-scale trials, only a very limited effect of improved flavour stability could be observed. In Chapter 6 a factorial experimental design was adopted to probe the interactions between seven factors known to impact on beer flavour stability. Chemical additions were made to a bright beer prior to bottling, to vary the following factors: total in pack oxygen, SO2, total iron, iso-α-acid and α-acid content, (+)-catechin and glutathione. Increased SO2 concentrations had the largest impact across the entire design space, resulting in reduced radical formation, staling aldehyde concentrations and improved sensory scores. The impacts of increased TIPO levels were rather limited. In contrast, a significant impact regarding the oxidative stability could be observed for increasing Fe concentration, highlighting the significance of pro-oxidative effects of transition metals.

Lambic beer is one of the oldest beer styles still being brewed in the western world today and the only beer that is still brewed through spontaneous fermentation. Lambic beers are only produced within a 500 km radius of Brussels because of the natural microflora found within the air in that region. Little is known about the chemical composition of lambic beers. The objective of this research were (1) to compare SPME and SAFE for the isolation of flavor and aroma compounds,  (2) determine the volatile composition and acids of commercially available lambic gueuze using SPME/GC-MS and HPLC, and (3) determine the major aroma compounds of aging lambic beer using GC-O.  Comparing the two extraction methods, both SPME and SAFE were able to identify a similar number of chemical compounds, however SAFE identified a greater number of acid compounds. A total of 50 compounds were identified within nine commercial brands of lambic beer. HPLC was used in the identification and quantification of acetic and lactic acids. The concentration of acetic acid in the commercial products ranged from 723 mg/L â " 1624 mg/L and lactic acid ranged from 995 â " 2557 mg/L. GC-O was used in the analysis of aged (3-28 months) lambic beer samples. As the samples increased in age, the number of aroma compounds detected by the panelists also increased. Panelists were detected nine aroma compounds in the 3 month old sample, while 17 compounds were detected in the 28 month old sample. The research conduct increased the number of volatile and semi-volatile compounds identified in lambic beer from 27 to 50.
Ph. D.

Thesis (PhD)--Stellenbosch University, 2005.
ENGLISH ABSTRACT: A number of relevant brewing industry issues associated with malt quality were examined. These included beer foam quality, premature flocculation of yeast during fermentation and antimicrobial factors in malt. The cause of poor foam at a brewery relative to other similar breweries was identified as being related to the boiling temperature during wort preparation and the associated conformational changes of the abundant foam protein lipid transfer protein 1 (LTPl). The temperature range of 96 to 102°C was revealed to be critical. At the higher temperature the denaturation of LTP 1 was more extensive and its effectiveness as a foam protein was reduced. In addition, it was shown that the prominent role of LTPI with respect to foam was as a lipid binding protein, forming a lipid sink and protecting foam from lipid damage. The occurrence of malt associated premature yeast flocculation (PYF) during fermentation was induced in malt by the addition of extra-cellular fungal enzymes to the malt husk or by micro-malting barley in the presence of fungi. In addition, treating malt husk with commercial xylanase or adding commercial arabinoxylan to the fermentation also impacted on yeast flocculation. It was proposed that a range of molecular weight arabinoxylans formed by the enzymatic breakdown of the major barley husk component (arabinoxylan) resulted in PYF. Antimicrobial activity against brewing yeast (Saccharomyces cerevisiae), other fungi and bacteria was found in barley, malt and malt derived wort trub. Wort trub is the non-specific precipitate of protein, polyphenols and lipids formed during wort boiling and which is, to some extend, carried over in the wort to the fermentation. Antimicrobial activity appeared to increase during malting. The growth of brewery collected yeast was inhibited in the presence of brewery production wort when compared to the same wort filtered to remove the trub. Brewery yeast was found to be more sensitive to inhibition than laboratory propagated yeast of the same strain. Different strains of S. cerevisiae were also found to differ in their sensitivity to inhibition. Investigation revealed that the activity originated from the inside of the barley grain and impacted on yeast sugar uptake. However, there was no direct correlation detected between levels of antimicrobial activity in malt and fermentation performance. At high concentrations the factors were microcidal causing cell lysis. Partial characterisation of an antimicrobial extract from malt revealed the presence of a factor between 5 and 14 kDa, containing a cationic peptide component. The optimum pH stability was ±5 when it was also most cationic. The factor easily and irreversibly lost activity at extreme pH and when exposed to certain reagents but was heat resistant in accordance with its survival in wort trub. Preliminary results showed the presence of LTP1 associated with other peptides in the active cationic fraction from the one malt tested. The occurrence of malt related PYF and malt antimicrobial factors are associated with microbial contamination of the grain. The fungi generating the PYF factors from the barley husk while the barley's defence mechanism generates antimicrobial factors to cope with the pathogenic effect of the fungi. In addition there is a potential link between the foam protein LTP 1 and malt antimicrobial activity as LTP 1 or LTP 1 in association with another component(s) is potentially antimicrobial.
AFRIKAANSE OPSOMMING: 'n Aantal problematiese areas in die broubedryf, wat met mout geassosieer word, is ondersoek, naamlik bierskuimkwaliteit, voortydige flokkulering van gis tydens fermentasie en die invloed van antimikrobiese faktore in mout. Die oorsaak van swak bierskuim by 'n spesifieke brouery relatief tot ander soortgelyke brouerye was geidentifiseer as die moutekstrakkookpunt tydens moutekstrakbereiding. Tydens hierdie proses ondergaan dieskuimprotein, lipiedoordrag proteien 1 (lipid transfer protein 1, LTPI), 'n konformasieverandering. Die temperature tussen 96 to 102°C was kritiek t.o.v. ideale konformasieverandering vir skuimaktiwiteit. Denaturering van LTPI het by hoër temperature plaasgevind wat die skuimproteien se aktiwitiet verminder het. Daar is ook bewys dat LTPI 'n verdere rol in bierskuim speel aangesien dit 'n lipiedbindingsproteien is wat die skuimnegatiewe lipiede verwyder. Die voorkoms van moutgeassosieerde voortydige flokkulering van gis (PYF) tydens fermentasie is op twee maniere in mout geinduseer, naamlik: • deur die toevoeging van ekstrasellulêre swamensieme tot die moutdop • deur mikrovermouting van gars in die teenwoordigheid van swamme. Die behandeling van die moutdop met kommersiele xilanase of die toevoeging van kommersiele arabinoxilaan by fermentasies het ook die flokkulering van gis beinvloed. Die hipotese was dat PYF veroorsaak is deur 'n reeks arabinoxilane met verskillende molekulêre massas wat gevorm het tydens die ensimatiese afbraakproses van die primere moutdopkomponent (arabinoxilaan). Antimikrobiese aktiwiteit teenoor brouersgis (Saccharomyces cerevisiae), ander swamme en bakterie was teenwoordig in gars, mout en moutekstrakpresipitaat. Die presipitaat bestaan uit nie-spesifieke presipitate van proteien, polifenole en lipiede wat gedeeltelik in die gekookte moutekstrak agterbly. Daar is gevind dat antimikrobiese aktiwiteit tydens vermouting toe geneem het. Die groeiproses van brouersgis, gekollekteer by 'n brouery, was geinhibeer deur die teenwoordigheid van brouery-geproduseerde moutekstrak in vergelyking met dieselfde moutekstrak wat gefiltreer was om die presipitaat te verwyder. Die brouersgis was meer sensitief heens inhibisie in vergeleke met dieselfde gisstam wat opgegroei is in die laboratorium. Verskillende S. cerevisiae stamme het ook verskille in sensitiwiteit getoon t.o.v. the antimikrobiese komponente in die moutekstrakte. 'n Verdere ondersoek het getoon dat die oorprong van die inhiberende aktiwiteit die interne dele van die gars is, asook dat dit die gissuikeropname beinvloed. Daar was egter geen direkte verband tussen antimikrobiese aktiwiteit in mout en fermentasie effektiwiteit, soos gemeet onder laboratorium toestande, nie. Hoë konsentrasies van die faktore het egter gelei tot seldood weens sellise. 'n Kationiese peptiedbevattende fraksie tussen 5 en 14 kDa en 'n optimale pH stabliliteit van 5 is gevind deur gedeeltelike karakterisering van 'n antimikrobiese moutekstrak. Die aktiewe fraksie se aktiwiteit is onomkeerbaar vernietig by ekstreme pH en blootstelling aan sekere reagense. Die aktiewe verbinding(s) is egter hittebestand en resultate het getoon dat hierdie aktiwiteit die brouproses oorleef as deel van die moutektrakpresipitaat. Voorlopige resultate van die een mout wat getoets is het die teenwoordigheid van LTP 1 getoon, asook die moontlike assosiasie met ander peptiede of kleiner komponente in die aktiewe kationiese fraksie. Die voorkoms van moutgeassosieerde PYF en antimikrobiese faktore in mout word met die mikrobiologiese kontaminasie van gars verbind. Swamme produseer die PYF faktore vanuit die moutdopkomponente, terwyl die plant weer antimikrobiese faktore produseer as deel van 'n beskermingsmeganisme teen die patogene effek van die swamme. Daar is ook 'n potensieele verwantskap tussen bierskuimproteien LTP 1 en antimikrobiese faktore in mout, aangesien LTPI ofLTPl tesame met 'n ander verbinding(s) moontlik antimikrobies is.

The objective of this research was to explore interactions between aroma compounds in simulated beef flavour (SBF) and soy protein isolate (SPI) that may be involved in the suppression of beefy notes in SBF by SPI. A sensitive and reproducible headspace solid phase microextraction (HSSPME) was established to isolate volatile compounds in SBF for analysis by gas chromatography (GC). Volatile and odour-active compounds in SBF were qualitatively evaluated by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) using detection frequency method, respectively. A total of 70 compounds were tentatively identified including three furans, six S-heterocyclic compounds, ten N-heterocyclic compounds, six aldehydes, three alcohols, and two esters. Of 49 volatile compounds detected in the sniffing port of GC-O, the most odour-active included 2-methyl-3-furanthiol, delta-3-carene, alphaterpinene, 2-ethyl-3,6-dimethylpyrazine, and several unidentified odourants. Descriptive analysis (DA) along with GC analysis was conducted to investigate changes in SBF aroma characteristics upon addition of SPI. Five attributes (beefy, roasted, yeasty, soymilk-like and cereal) were selected to assess various mixtures of SBF and SPI. The results from DA confirmed that "roasted", "beefy" and "yeasty" notes were highly positively correlated with SBF concentration, and the beefy related notes were substantially suppressed by increasing SPI content. Fifteen peaks from GC analysis were selected as indicator peaks to represent beef attribute in the mixtures of SPI and SBF. Changes in the release of beefy aroma components of SBF by addition of ingredients (glucosamine, sucrose, ascorbic acid, and/or polyethylene glycol) to SPI and the changes in SPI protein structure induced by the ingredients were investigated. The reduction of disulfide bonds, increased surface hydrophobicity and increased unordered structure in SPI containing ascorbic acid alone or with polyethylene glycol, along with increased GC peak areas of indicator peaks in those SPI-SBF mixtures, were found to be associated with an increase in the perceived beef characteristic attributes in descriptive analysis. These results provide the basis for further research to elucidate strategies maximizing perception of beefy aroma in soy based products.
Land and Food Systems, Faculty of
Graduate

Orientador : Roberto Herminio Moretti
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: A cerveja tipo Pilsen é líder de vendas no mercado mundial. Ocorre mundialmente a tendência de se produzir cervejas Pilsen com menos amargor, menos corpo e mais claras. O grande desafio atual da indústria cervejeira é a garantia do frescor e leveza desse produto durante todo o seu tempo de vida de prateleira. Com a globalização, as cervejas são transportadas para distâncias cada vez maiores, causando a demanda por um produto que contenha vida de prateleira estendida, ou seja, grande estabilidade sensorial. Níveis mínimos de aromas e sabores indesejados são facilmente percebidos pelo consumidor, pois os teores de amargor, corpo e álcool são insuficientes para mascará-los. Neste trabalho foi avaliada a influência de importantes variáveis sobre a estabilidade sensorial da cerveja Pilsen. Os efeitos da temperatura, da incidência de luz e da agitação durante o transporte da cerveja, bem como da interação entre eles, foram quantificados e, pela primeira vez, comparados estatisticamente. A literatura cita a influência destas variáveis, mas sua quantificação, interação e comparação, não estão relatados. Os resultados mostraram que a influência da temperatura sobre a estabilidade da cerveja é muito maior que os efeitos de agitação e de incidência de luz. Esses dois últimos, por sinal, têm pouco ou nenhum efeito sobre a estabilidade sensorial do produto. Esses resultados foram validados estatisticamente, tanto por provadores treinados de uma cervejaria comercial, quanto por consumidores comuns. Em oposição ao resultado sensorial, a formação de trans-2-nonenal se mostrou mais influenciada pela incidência de luz e pela agitação, do que pela ação da temperatura, reforçando a corrente de que o teor de trans-2-nonenal não é, por si só, um bom indicador da estabilidade sensorial da cerveja. Este trabalho traz, ainda, uma ferramenta inédita e muito importante para a tomada de decisões por parte dos cervejeiros. Decidir se uma cerveja pode ou não ser liberada para consumo é uma das tarefas desses profissionais. O critério de liberação pela análise sensorial do produto leva um grau muito alto de subjetividade. Primeiramente, é apresentada uma visão do grau de aceitação do consumidor em relação à oxidação da cerveja, representada aqui pelos níveis dos atributos papelão, caramelo e metálico. Provadores foram treinados usando a técnica de Análise Descritiva Quantitativa (ADQ), para avaliação sensorial desses três atributos. A combinação da análise estatística dos resultados dos testes de aceitação com os resultados da equipe de ADQ permitiu a construção de um modelo matemático, que é uma ferramenta adequada para a decisão objetiva quanto a comercializar ou não uma cerveja. Com essa ferramenta se elimina a subjetividade da decisão do provador, por mais técnica e respeitada que esta seja na indústria de cerveja. Dentre os atributos sensoriais utilizados para descrever a oxidação da cerveja, a intensidade do atributo papelão é a que tem maior correlação com a estabilidade sensorial do produto. Os atributos caramelo e metálico não apresentaram correlação nem com a opinião dos provadores treinados da cervejaria nem com a aceitação dos consumidores
Abstract: Pilsner is the type of beer produced the most worldwide. There is a global trend to produce beers that are not exactly like the original Pilsner beer: less bitter, less body and paler. The most challenging problem for the breweries at the moment is to guarantee the freshness of this beer during its shelf life. Global sales and markets result in beers being distributed to longer distances and this demands a longer shelf life with high flavor stability. Consumers easily detect minimum contents of off-flavors because the low bitterness, low alcohol content and low body are not capable of masking them. In this work the influence of important variables on Pilsner beer flavor stability was studied. The impact of temperature, exposure to light and shaking during transportation, as well as the interaction between them, were quantified and, for the first time, statistically compared. The current available reports mention the influence of these three variables over the beer quality, but it is not clear witch is the most important nor how is the interaction between them. According to the results obtained here, the temperature plays a major role when compared to shaking and light exposure. In fact, the former two effects showed to have low or even no effect on the stability of the product. Both a trained panel of a commercial brewery and regular consumers had statistically validated this conclusion. Oppositely, the formation of trans-2-nonenal is more influenced by light exposure and shaking than by temperature. This reveals that the content of trans-2-nonenal is, alone, not enough to express beer flavor stability. This thesis also brings a unique sensory tool to be used by the brewers to decide whether a supposedly oxidized beer can or cannot be dispatched to market. Currently, this decision is made on a subjective basis by judging the freshness of the beer or even the freshness it might present during its shelf life. Judging how much a beer is oxidized is not a simple task and most of the time this is done by only some brewers (sometimes only one), what increases the risk. The acceptance by consumers is here related to the beer oxidation, represented by the attributes papery, caramel and metallic. Subjects were trained to judge the contents of these attributes in the beer using the Quantitative Descriptive Analysis (QDA) technique. The statistical combination of the results of the beer acceptance and the results of the QDA allowed the construction of a mathematical model for deciding objectively about selling or not a beer. With this tool the subjective decision of the taster is eliminated, even though this it is commonly practiced and respected in the beer industry. Concerning the beer attributes used in this work to describe the beer oxidation, the intensity of the attribute papery is the one that is more strongly correlated with the flavor stability of the product. The attributes caramel and metallic do not correlate neither with the opinion of the trained panel nor with the acceptance by the consumers
Doutorado
Doutor em Tecnologia de Alimentos

Liver off-flavor is a sporadic problem that limits the consumer acceptance of several beef chuck muscles, including the infraspinatus (flat iron steak). Residual blood hemoglobin is known to contribute to liver off-flavor development. This study was conducted to evaluate factors affecting development of liver off-flavor after cooking of beef chuck (shoulder) muscles. The study was conducted in three parts. The objective of part 1 was to determine effects of muscle (infraspinatus, longissimus dorsi, serratus ventralis, supraspinatus, teres major) and processing (with or w/o carcass electrical stimulation) on residual blood hemoglobin content and total pigment content of raw muscle and sensory characteristics after cooking to 71 or 82?C. The objective of part 2 was to evaluate the effect of antioxidant treatment and anaerobic packaging to possibly reduce the incidence of liver and other off-flavors of beef infraspinatus (IF) steaks. The objective of part 3 was to determine the effect of animal age (commercial grade; >42 months, compared to select grade; <30>months), antioxidant treatment, and anaerobic packaging on sensory characteristics of beef IF steaks. Among beef chuck muscles, the infraspinatus had highest mean liver flavor score of 2.08±1.00 where 2=slightly intense liver flavor. Other muscles (longissimus dorsi, serratus ventralis, supraspinatus, teres major) had mean liver flavor scores less than 2. Liver flavor score, myoglobin, hemoglobin, and total pigment content were higher (p<0.05) for infraspinatus muscle from older animals. Among select grade muscles, carcass electrical stimulation had no significant effect on liver flavor score. Rancid flavor scores were significantly increased from 1.34±0.65 to 1.58±0.84 as internal cook temperature increased from 71 to 82°C but mean TBA values as a measure of rancidity (0.25±0.15 and 0.29±0.13, respectively) were not affected by cook temperature. Antioxidant treatment significantly reduced TBA values, rancid, and liver flavor scores for aerobically packaged steaks (PVC or 80% O2-MAP) but had little effect on scores of steaks in anaerobic packaging (0.4% CO-MAP). Results of this study indicate that infraspinatus steaks from older animals are most likely to have objectionable liver, sour/grassy, or rancid flavors. Objectionable flavor scores were lower in steaks receiving antioxidant injection or packaged anaerobically in 0.4% CO-MAP.

Flavor lexicons are used in sensory evaluation to determine the flavor profile of a food product. The objective of this study was to develop a flavor lexicon for cooked beef, which can then be used in various projects relating to beef quality such as studies investigating animal diet, marinating, ageing, or other enhancements. A descriptive panel of 10 people was used to develop a flavor lexicon of 18 attributes, including astringent, barny, bloody, brothy, browned, gamey, grassy, juicy, fatty, livery, metallic, oxidized, roast beef, and the five basic tastes (bitter, salty, sour, sweet, and umami). In contrast to other studies on beef, this lexicon was developed to include both positive and negative attributes. The lexicon was able to show that rib eye steaks from the Longissimus dorsi muscle in grass-fed animals were significantly (p<0.05) higher in barny, bitter, gamey, and grassy flavors, and lower in juicy and umami flavors. The steaks were also rated by consumers, who showed a preference for grain-fed beef over grass-fed beef. The ratings of the descriptive panel were related to the consumer panel scores to equate the lexicon terms with a positive or negative consumer degree of liking score. Those terms that were considered positive in this study due to their positive correlation with consumer liking include brothy, umami, roast beef, juicy, browned, fatty, and salty. The terms that were inversely associated with consumer liking were barny, bitter, gamey and grassy, among others. A separate descriptive panel was conducted on the Spinalis dorsi (or “cap” muscle) of the rib eye steak, with similar results. Additionally, descriptive and consumer evaluations found no difference between two types of grass diets, namely alfalfa and sainfoin. Different mixtures of beef and chicken were also evaluated to determine flavor differences between the two meats. Chicken was found to be more closely correlated to brothy, juicy, sweet, and umami, among others, while beef was found to be more closely correlated to terms such as gamey, bloody, oxidized, metallic, roast beef, and astringent. Throughout these tests, the newly developed lexicon was shown to be an effective tool for profiling fresh meat samples.

The impact of colour adjustment on the flavour stability of a portfolio of locallybrewed pale lager beers with a range of colouring agents such as specialty malts, roasted barley, colouring beer and artificial caramel colorant was investigated. All brewing control parameters and beer specifications were defined and monitored under a rigorous regime in order to avoid processing factors that might interfere with or modify the two parameters under investigation. The colour appearance parameters of the beer samples at distinct ages (fresh, forced aged and 12 month-aged) were psychophysically assessed by means of sensory viewing method (magnitude estimation) by an expert panel of the Colour Imaging Group at the Department of Colour Science, University of Leeds. Likewise, the aforementioned samples were physically measured by tele-spectroradiometry and digital imaging system at two different environments. Significant differences between the beer samples at sameand distinct ageing conditions were detected in terms of lightness, colourfulness, hue angle, opacity and clarity, although all of the samples were colour-adjusted to the same colour units according to conventional procedures (EBC colour units). In addition, good agreement between the sensory viewing (magnitude estimation) method and telespectroradiometry was observed. In contrast, some discrepancies between the aforementioned methodologies and the digital imaging technology were detected. Flavour stability was assessed by the detection and quantification of fifteen flavour-active beer ageing compounds (10 aldehydes and 5 non-aldehydes compounds) by GC-MS using headspace-solid phase microextraction (HS-SPME) with on-fibre PFBOA [O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine] derivatisation for aldehydes compounds and on-fibre DVB-CAR-PDMS [divinylbenzene-carboxenpolydimethylsiloxane 50/30_m] derivatisation for non-aldehyde compounds. The results were correlated with the determination of the endogenous anti-oxidative potential (EAP) of the beer samples by electron spin resonance (ESR) using N-tert-butyl-α-(4- pyridyl)nitrone N’-oxide (POBN) and the sensory assessments provided by the I.C.B.D. sensory panel. Additionally, the quantification of organic radicals of the specialty malts, the roasted barley (whole intact kernel and milling fraction measurement) and the artificial caramel colorant were conducted by ESR. Based on the results of this holistic approach, a colouring agent was selected for improving the flavour stability of pale lagers according to its physicochemical-, sensorial and psychophysical effects as colour appearance.

Hops (Humulus lupulus L.) are an indispensable component of beer, with the essential oil responsible for imparting distinctive odour and aroma characteristics to beer. However, not all character-impact odorants in hop essential oil have been identified and hop aroma in beer is still not completely understood. The composition of hop essential oil is very complex with 485 compounds currently identified in the literature, and recent research suggests that up to 1000 compounds may actually be present. Only a certain number will be present at concentrations above threshold and make a direct contribution to the odour of the oil. In addition, many important odorants are only present at trace concentrations. Gas chromatography-olfactometry (GC-O) using human assessors is the best way to locate potent odorants and facilitate their identification. A novel methodology was developed to identify the character-impact odorants in hop essential oil samples using hyphenated techniques in gas chromatography. GC-O was used to locate odour active compounds and determine relative importance using CharmAnalysis[TM] according to the odour potency principle. Due to the chemical complexity of the samples, considerable co-elution of peaks occurs during single column gas chromatography (1DGC), making the detection and identification of character-impact odorants challenging. Therefore, comprehensive two-dimensional gas chromatography (GCxGC) combined with time-of-flight mass spectrometry (TOFMS) was used to resolve and identify compounds eluting in the odour active regions. The methodology was developed in a case study on coriander (Coriandrum sativum) and wild coriander (Eryngium foetidum) leaf essential oils. During GC-O analysis of these samples it was recognised that odour active regions frequently coincide with several co-eluting compounds. To address this, a heart-cut multidimensional gas chromatography-olfactometry (MDGC-O) instrument was developed to resolve these 'co-eluting odour clusters' and determine the compound(s) responsible for the odour perception. The 'spicy' character of hops is considered to be a desirable attribute in beer associated with 'noble hop aroma'. However, the compounds responsible have yet to be adequately elucidated. This character was investigated using a commercial 'Spicy' fraction of hop essential oil, selectively enriched for monoterpene and sesquiterpene alcohols. The odour active compounds in (i) the spicy fractions and (ii) the whole essential oils of four different hop varieties were compared using the presented methodology. A compound with an intense 'woody, cedarwood' odour was determined to be a potent, character-impact odorant in all samples. This odour coincided with a complex region of the chromatogram where up to thirteen compounds were co-eluting. The peak responsible for this odour was determined by (i) correlation of peak areas with odour potency (Charm) values and (ii) MDGC-O. The compound was tentatively identified by GCxGC-TOFMS as 14-hydroxy-β-caryophyllene, which has not previously been reported as an odorant in hop essential oil. It was concluded that this compound and other 'woody, cedarwood' odorants contributed to the 'spicy' character of the investigated hop samples. Compounds previously associated with noble hop aroma, notably caryophyllene oxide, humulene epoxides I and II, and humulenol II, did not contribute to the odour character of the hop samples. Other potent odorants that were identified in the whole essential oil and spicy fractions of hops were: geraniol, linalool, β-ionone, eugenol, isovaleric acid, and β-damascenone. While myrcene was a moderately potent odorant in the whole hop essential oil samples, the abundant sesquiterpene hydrocarbons α-humulene, β-caryophyllene and β-farnesene did not significantly contribute to the odour character.

Master of Science
Department of Animal Sciences and Industry
Terry Houser
A total of 45 top sirloin butts (IMPS 184) were procured from three commercial beef processing facilities to determine the effects of post-mortem aging time and blade tenderization on the quality of beef gluteus medius (GM) steaks. Top sirloin butts were randomly assigned to five post-mortem aging periods (5, 19, 33, 47, and 61 days). One-half of each beef GM was randomly assigned to either a blade tenderized treatment or a non-blade tenderized treatment that was not blade tenderized. Steaks were then evaluated for thiobarbituric acid reactive substances (TBARS), metmyoglobin reducing activity (MRA), oxygen consumption rate (OCR), visual color panel, instrumental color, Warner-Bratzler shear force (WBSF), Lactic Acid Bacteria (LAB) enumeration, pH, and sensory properties. Aging × blade tenderization interactions (P < 0.05) were found for display color panel, discoloration panel, WBSF, overall tenderness, myofibrillar tenderness, bloody/serumy, metallic, overall sweet, and bitter (P < 0.05). As steaks were aged longer and blade tenderized they became more discolored during display and more tender. In addition, there were aging × display time interactions (P < 0.05) observed for L*, a*, b*, display color panel, and discoloration panel. As steaks were aged longer, they had increased L*, a*, b*, and hue angle values and display color panel scores when initially put into a retail case, but L*, a* and b* decreased and discoloration scores increased as display time increased. Furthermore, there were blade tenderization × display time interactions (P < 0.05) found for display and discoloration panels. Blade tenderized steaks discolored faster in retail display than non-blade tenderized steaks. With increased aging time, there was an increase (P < 0.05) in TBARS, OCR, initial color panel, LAB enumeration, and warmed-over flavor, as well as a decrease in MRA. Also, as aging increased there was a decrease (P < 0.05) in MRA, initial color panel scores, and WBSF values. Blade tenderization significantly increased (P < 0.05) initial color panel scores, rancid flavor, and spoiled flavor. Increasing the aging time of the GM, produced steaks with decreased color stability, altered the flavor profile, and increased tenderness. Blade tenderization significantly increased tenderness, increased discoloration in a retail case, and produced more undesirable flavors.

This study determined how quality grade and degree of doneness influence the development of beef flavor compounds among whole muscle and ground patties. Proximate composition, pH, cooking duration, neutral and polar lipid fatty acids, free and total amino acids, total reducing sugars, and volatile compounds were evaluated in beef strip steaks and ground patties of Longissimus lumborum from three USDA quality grades (Prime, Low Choice, and Standard; n=8 per quality grade) and six degrees of doneness (4, 25, 55, 60, 71, and 77°C). In the split-plot experiment, quality grade was the whole-plot, product-type was a sub-plot, and degree of doneness was the sub-sub-plot. The 3-way interaction of quality grade, degree of doneness, and product type impacted moisture (P = 0.004) and protein content (P = 0.006); pH (P < 0.001); neutral and polar lipid fatty acids (P ≤ 0.048); free and total amino acids (P ≤ 0.044); total reducing sugars (P < 0.001); and volatile compounds (P ≤ 0.029). The 2-way interaction of quality grade and degree of doneness impacted free amino acids (P ≤ 0.036); PUFA within the neutral lipid fraction (P ≤ 0.033); fatty acids within the polar lipid fraction (P ≤ 0.043); volatile compounds (P ≤ 0.038); and the total fat percentage (P = 0.046). The 2-way interaction of quality grade and product type impacted fatty acids within the neutral lipid fraction (P ≤ 0.042); fatty acids within the polar lipid fraction (P ≤ 0.015); and volatile compounds (P ≤ 0.047). The 2-way interaction of product type and degree of doneness affected fatty acids within the neutral lipid fraction (P ≤ 0.046); fatty acids within the polar lipid fraction (P ≤ 0.035); free amino acids (P ≤ 0.005) and total amino acids (P ≤ 0.004); volatile compounds (P ≤ 0.029); and cooking duration (P < 0.001). Overall the results of this study indicated that quality grade, grinding, and cooking have interacting effects on flavor related compounds. Thus, each factor must be considered during any model development which aims to predict beef flavor.

Orientador: Maria Aparecida A. P. da Silva
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-05T15:54:43Z (GMT). No. of bitstreams: 1 Almeida_SelmaBergara_D.pdf: 1651470 bytes, checksum: a5ee60dbc52c3dc1aeab330822f4380b (MD5) Previous issue date: 2006
Resumo: Para a recuperação do aroma e sabor de fruta fresca ao suco industrializado, subprodutos do processamento do suco de laranja, como óleo essencial e essências aquosa e oleosa, são normalmente reincorporados ao produto processado. A adição de cada um desses subprodutos confere ao produto final qualidade e estabilidade sensoriais distintas. O presente trabalho teve por objetivo avaliar a qualidade e estabilidade sensoriais do suco de laranja reconstituído, produzido com laranjas de variedades brasileiras e aromatizado com quatro diferentes aromas naturais de laranja, quais sejam: I - óleo essencial; II - frações destiladas de essência oleosa (oil phase); III - aroma formulado contendo frações destiladas de óleo essencial e de essência oleosa; e, IV - aroma formulado contendo frações destiladas de óleo essencial, frações destiladas de essência oleosa e de essência aquosa (water phase). Assim, esta pesquisa consistiu em quatro etapas, a saber: avaliação do impacto dos quatro aromas naturais sobre a aceitação e perfil sensorial do suco de laranja pronto para beber em condições pré-processamento térmico; avaliação da estabilidade sensorial dos aromas naturais ao processamento térmico do suco; avaliação do impacto dos aromas naturais sobre a estabilidade sensorial do suco pronto para beber durante o armazenamento da bebida e, finalmente, a identificação de compostos voláteis odoríferos presentes em um dos aromas mais estáveis - Aroma III. Quatro formulações de suco de laranja reconstituído foram elaboradas, adicionando-se os aromas I, II, III e IV, processadas e envasadas assepticamente em garrafas PET. Os perfis sensoriais, através de Análise Descritiva Quantitativa, e a aceitação das quatro formulações de suco de laranja pronto para beber foram avaliados antes e após o processamento térmico, bem como durante o armazenamento da bebida por 20, 40, 60 e 90 dias. Índices de escurecimento e teores de vitamina C foram determinados durante o armazenamento. Adicionalmente, amostras comerciais de suco de laranja pronto para beber foram avaliadas. Os dados foram analisados por ANOVA, teste de média Tukey ou t-Student, Mapa de Preferência, Análise de Componentes Principais, análise de correlação de Pearson e análise de regressão linear dos parâmetros sensoriais em função do tempo de armazenamento da bebida. O aroma III foi avaliado por cromatografia gasosa (CG), CG-olfatometria (Osme) e espectrometria de massas. Os resultados obtidos na primeira etapa da pesquisa sugeriram que a reincorporação dos compostos voláteis provenientes da essência oleosa contribuem menos para aumentar a aceitação do suco de laranja do que aqueles provenientes do óleo essencial. Em contrapartida, as amostras comerciais tiveram aceitação modesta entre os consumidores indicando que, no Brasil, os sucos de laranja comerciais podem ainda ter sua qualidade sensorial melhorada pela adição de novos aromas naturais. Na segunda etapa, a avaliação da aceitação das amostras pré e pós-processamento indicou boa estabilidade dos aromas naturais estudados ao processamento térmico. Os perfis sensoriais das formulações sugeriram que: i) a reincorporação ao suco de frações destiladas dos três subprodutos do processamento da laranja, resulta em maior estabilidade térmica do que aromas derivados apenas do óleo essencial; e, ii) a presença de voláteis provenientes da essência aquosa no aroma natural de laranja, mesmo que em proporções minoritárias, realça no suco notas de sabor de suco natural e suaviza as notas de aroma e sabor de casca de laranja. Na terceira etapa, durante o armazenamento da bebida, a formulação contendo apenas frações de essência oleosa apresentou, notadamente, menor estabilidade sensorial do que as demais formulações, contendo compostos voláteis provenientes do óleo essencial. Possivelmente essa ocorrência seja devida à presença de agentes antioxidantes naturais nas frações derivadas do óleo essencial. Adicionalmente, os resultados sugeriram que a adição ao suco de laranja de frações destiladas de óleo essencial resulta em melhor estabilidade sensorial à bebida do que a adição ao suco do óleo essencial na sua forma integral. Em todas as amostras, ao longo do período de armazenamento, ocorreu queda dos teores de vitamina C e concomitante escurecimento dos sucos. Finalmente, na última etapa, foram gerados 55 picos de odores, os quais apresentaram, predominantemente, notas de aroma associadas à laranja. Beta-mirceno, butanoato de etila, a-pineno, hexanal, citral e decanol foram os compostos voláteis de maior importância odorífera identificados. Os compostos ß-terpineol, citronelal, undecanal, acetato de a-terpenila, acetato de nerila e a-cariofileno foram identificados como compostos de alto poder odorífero e, limoneno, linalol, a-terpineol e decanal, como compostos de baixo poder odorífero
Abstract: To restore the natural orange aroma and flavor to industrialized juices, processors add natural flavorings obtained from three orange juice by-products: the cold-pressed oil, the oil phase and the water phase. The addition of each of these by-products results in juices with distinct sensory characteristics and acceptability. The present work aimed at evaluating the sensory quality and stability of reconstituted orange juice from Brazilian varieties, flavored with four different orange natural aromas, which are: I ¿ essential oil; II ¿ distilled fractions of the oil phase; III - formulated aroma containing distilled fractions of the essential oil and of the oil phase e, IV ¿ formulated aroma containing distilled fractions of the essential oil, distilled fractions of the oil phase and of the water phase. Thus the present research was divided into four stages: evaluation of the impact of four natural aromas (I, II, III, IV) on the acceptability and sensory profile of ready-todrink orange juice before thermal treatment; evaluation of the sensory stability of the natural aromas to the thermal treatment of the juice; evaluation of the natural aromas impact to the sensory stability of ready-to-drink orange juice during storage; the identification of odor volatiles compounds in one of the most stable aromas ¿ Aroma III. Four reconstituted orange juices formulations were elaborated, by adding the above mentioned flavorings (I, II, III, IV), processed and packed in PET bottles. The sensory profiles, by using Quantitative Descriptive Analysis, and the acceptability of the four ready-to-drink orange juices were evaluated before and after the processing, and also during their 20, 40, 60 and 90 day-storage. In addition, other commercial samples of ready-to-drink orange juice were included in this study. Determinations of the ascorbic acid and the browning index of formulated juices were done as well. Data were analyzed by ANOVA, Tukey or t-Student mean test, Principal Component Analysis, Preference Mapping, Pearson¿s correlation analysis and linear regression analysis of sensory parameters as a function of the storage time. The aroma III was evaluated by gas chromatography (GC), GC-olfactometry (OSME) and by mass spectrometry. The results obtained from the first research stage suggested that reintroduction of the volatiles compounds from oil phase contribute less to increase the acceptability of orange juice than those from the essential oil. On the other hand, all the commercial samples presented moderate acceptability by consumers, indicating that the commercial orange juices in Brazil may have their sensory quality improved by adding new natural aromas. In the second research stage, the evaluation of the pre and post-processing samples acceptability indicated that the studied natural aromas presented good stability to the thermal treatment. The formulations sensory profiles suggested that: i) the reintroduction of the distilled fractions of the three orange processing by-products to the juice results in higher thermal stability than that caused by the aromas derived from the essential oil; ii) the presence of volatiles from distilled fractions of the water phase in the natural orange aroma, although in very small proportions, enhances natural juice flavor and softens orange peel flavor and aroma. In the third research stage, during the drink storage the formulation containing only distilled fractions of the oil phase presented much less sensory stability than the other formulations, containing volatile compounds from the essential oil. A possible explanation for this occurrence is the presence of natural antioxidants in those fractions derived from essential oil. Further, the results suggested that the addition of distilled fractions of essential oil to orange juice provides better sensory stability to the drink than the addition of the integral essential oil. During storage all samples showed decrease in vitamin C and simultaneous browning of juices. Finally, in the last research stage, Fifty-five odor peaks were generated, which presented aroma notes associated mostly to orange. Beta-myrcene, ethyl butanoate, a-pinene, hexanal, citral and decanol were identified as the highest aroma impact compounds. The compounds ß-terpineol, citronellal, undecanal, a-terpinyl acetate, neryl acetate and a-cariophylene were identified as high odor power compounds and, limonene, linalool, a-terpineol and decanal, as low odor power compounds
Doutorado
Doutor em Tecnologia de Alimentos

This diploma thesis deals with preparation and characterization of alcohol-free beers with different flavours. Five flavoured and four pure, commercially available beers were tested. Three alcohol-free beers were then selected and used for preparation of flavoured beers. Ingredients used for production of flavour were honey, raspberry, ginger and cranberry. Analysis was focused mainly on substances of phenolic nature. Flavoured beers were also tested in sensory analysis. Ingredients used for flavouring of beers and production of both alcoholic and alcohol-free beers are described in theoretical part of the thesis. Analysis of polyphenols, flavonoids, technological characteristics and anthocyanins was performed using spectrophotometric method. Phenolic substances were identified and quantified by HPLC/PDA. Ascorbic acid was analysed by HPLC-NH2/UV. Results proved an increase of polyphenols, ascorbic acid and anthocyanins during flavouring of alcohol-free beers in dependence of used ingredients. Sensory analysis showed that as the best rated was the Staropramen beer with raspberry flavour. On the contrary, flavoured Bernard beers were poorly rated.

Esse trabalho foi conduzido com o objetivo de avaliar os efeitos da inclusão de óleo de soja ou de teores de caroço de algodão (CA) em dietas contendo alto teor de concentrado para bovinos confinados. No experimento I foram utilizados seis bovinos machos, castrados, da raça Nelore (407 ± 24 kg de peso corporal), distribuídos em um delineamento em Quadrado Latino 6 x 6. Foram avaliados 5 teores de inclusão (0, 8, 16, 24 e 32%) de CA em dietas contendo 80% de concentrado (tratamentos CA0, CA8, CA16, CA24 e CA32, respectivamente). Além disso, foi avaliada uma dieta contendo o mesmo teor de lipídios totais da dieta CA32, porém sem a inclusão de caroço de algodão, utilizando óleo de soja (tratamento OS). A inclusão de caroço de algodão na dieta reduziu (efeito linear, P < 0,01) o consumo de matéria seca e o consumo de matéria orgânica dos animais. A digestibilidade aparente total da MS (P = 0,019) e da MO (P = 0,020) reduziu linearmente devido à inclusão de CA na dieta dos animais. A inclusão de óleo de soja na dieta não afetou o digestibilidade da MS (P = 0,462) e da MO (P = 0,469) dos animais em comparação aos animais alimentados com a dieta controle, sem CA, assim como também não foram observados efeito da fonte de lipídios sobre a digestibilidade da MS (P = 0,124) e da MO (P = 0,110). O tempo de ruminação aumentou linearmente (P = 0,002) em resposta a inclusão de CA. O pH ruminal dos animais aumentou (efeito quadrático, P < 0,05) em resposta à inclusão de caroço de algodão nas dietas. O inclusão de óleo de soja na dieta não afetou (P = 0,329) o pH ruminal dos animais em comparação com a dieta controle sem CA. A produção total de ácidos graxos de cadeia curta reduziu (P < 0,001; efeito linear) devido à inclusão de CA. A síntese de Pmic reduziu linearmente (P = 0,011) em resposta a inclusão de CA na dieta. No experimento II, foram utilizados 280 bovinos machos, da raça Nelore e peso médio inicial de 349 ± 33 kg, distribuídos em 40 baias. O delineamento utilizado foi blocos incompletos casualizados. O máximo peso final foi obtido com inclusões de 7,6% de CA. A inclusão de CA na dieta reduziu o CMS dos animais (P < 0,001). A inclusão de óleo de soja reduziu o CMS dos animais (P < 0,05) em comparação com os animais alimentados com a dieta controle sem caroço de algodão. O máximo GPD foi observado com 8% de inclusão de CA na dieta. A máxima EA ocorreu com 14,5% de CA na dieta. Os dados referentes as característica da carcaça (PQC, RC, AOL e EGS) também apresentaram resposta quadrática (P < 0,05) à inclusão de CA na dieta. Comparado ao tratamento controle, sem CA na dieta, a inclusão de óleo de soja não afetou nenhuma das características da carcaça avaliadas (P > 0,05). As características químicas da carne não diferiram (P > 0,05) entre os animais alimentados com dietas contendo 32% de CA daqueles alimentados com óleo de soja. A oxidação dos lipídios (TBARS) apresentou redução (efeito quadrático; P = 0,035) devido à inclusão de CA na dieta. Na avaliação sensorial da carne assada realizada através do painel consumidor, não foram observados efeitos dos tratamentos sobre o sabor, odor e aceitabilidade geral da carne (P > 0,05). Na avaliação das características organolépticas da carne realizada pelos provadores treinados também não foram observados efeitos dos tratamentos sobre o odor, sabor e aceitabilidade geral (P > 0,05). No experimento III, avaliou-se a cinética de fermentação ruminal do milho e do caroço de algodão através da produção cumulativa de gases. Foram utilizados cinco frascos (repetições) contendo 1g de substrato (milho ou CA) além de 5 frascos “brancos” (sem substrato). As leituras de pressão e volume dos gases acumulados nos frascos de incubação foram realizadas com transdutor de pressão nos tempos 0, 2, 4, 6, 8, 10, 12, 15, 19, 24, 30, 36, 48, 72 e 96 horas. O milho apresentou um maior potencial de produção de gases quando comparado ao caroço de algodão (P < 0,001). O tempo de colonização não apresentou diferença entre as duas fontes de energia (P = 0,646). O caroço de algodão apresentou uma maior taxa de degradação comparado com o milho (P = 0,001) e, consequentemente, para a redução (P < 0,001) do tempo necessário para atingir a máxima produção de gás. O milho apresentou uma maior potencial de degradação quando comparado com o caroço de algodão, resultado esse que pode ser observado pelo maior produção de gases. Apesar não suportar um grande potencial de degradação, parte da fração fribrosa do caroço de algodão apresentou alta degradabilidade, o que pode ser observado na sua maior taxa de degradação quando comparado com o milho
Three trials were conducted to evaluate the effects of the inclusion of levels of whole cottonseed (WC) or soybean oil (SO) in diets for Nellore feedlot cattle. In the experiment I six rumen-cannulated Nellore steers (407 ± 24 kg BW) were used in a 6 x 6 Latin square design experiment. Were evaluated 5 levels of inclusion of WC (0, 8, 16, 24 and 32% DM basis) in diets containing 87% concentrate (treatments WC0, WC 8, WC16, WC24 and WC32 respectively). Also, it was evaluated a diet containing the same amount of total fat content of WC32 but with no WC and using soybean oil (SO treatment). Increasing WC levels linearly decreased DM and OM intake (P < 0.01). CP and NDF intakes were not affected by the treatments. Total fat digestibility linearly increased due the WC increase in the diets (P < 0.001). Total DM (P = 0.019) and OM (P = 0.020) digestibilities linearly decreased with increasing levels of WC. SO inclusion did not affect DM (P = 0.462) and OM (P = 0,469) digestibilities compared with CA0 and there was no effect of fat source over DM (P = 0.124) and OM (P = 0.110) digestibilities. Rumination time linearly increased due the WC inclusion (P = 0,002). Increasing WC levels quadratically increased ruminal pH (P < 0.05) but no effect was observed with the SO addiction in the diet (P = 0.329) compared with CA0. Total VFA was linearly decreased with increasing levels of WC (P < 0.001). Increasing levels of WC linearly decreased the microbial protein synthesis (P = 0.011). In the experiment II a total of 280 Nellore bulls (initial BW = 349 ± 33 kg) were allotted in 40 pens. The statistical design was randomized incomplete blocks. The maximum final BW was obtained with 7.6% of inclusion of WC. Increasing levels of WC decreased DMI (P < 0.001). Adding SO also decreased DMI (P < 0.05) compared with WC0. Increasing the inclusion rate of WC quadractically increased the ADG, G:F, HCW, dressing percent, LM area and 12-rib fat (P < 0.05). The maximum ADG were obtained with 8% of inclusion of WC. On the other hand, the maximum G:F was obtained with 14.5% of WC. Compared with WC0, the SO inclusion did not affect carcass characteristics (P > 0.05). The inclusion of WC quadractically affect meat composition (P < 0.05). Compared with CA32, the inclusion of SO in the diet did not affect the meat composition. Increasing WC in the diets quadratically decrease (P = 0.035) lipid oxidation. No effects were observed in the sensorial evaluation flavor, taste and overall acceptability by the costumers (P > 0.05). Training sensory panelists also did not find differences between the treatments for flavor and taste. Increasing WC linearly decreased the tenderness (P = 0.045). Compared with CA32, the inclusion of SO increased meat tenderness (P = 0.031). In the experiment III was evaluated the ruminal fermentation kinetics of corn and cottonseed through the in vitro gas production technique. Five bottles for each energy source (corn and cottonseed), plus five additional bottles containing buffered medium and rumen fluid inoculum only (blanks) were used. The volume of gas produced was recorded at 0, 2, 4, 6, 8, 10, 12, 15, 19, 24, 30, 36, 48, 72 e 96 h of incubation using the pressure reading technique. Gas values were corrected for blank incubations. The corn had greater gas production than cottonseed (P < 0.001). Lag time was not different between the two energy sources (P = 0.646). Cottonseed had higher FDR than corn (P = 0.001) and shorter time to half asymptote (P < 0.001). Corn had higher potential of degradation compared with cottonseed observed by the higher gas production. Moreover, even with lower potential of degradation, the cottonseed fibrous fraction had a high degradability compared to corn

O sabor da cerveja é determinado pela matéria-prima, pelo tipo de processo e pela levedura utilizada, além dos compostos produzidos durante a fermentação e maturação, que exercem maior impacto. A produção de amidos modificados é uma alternativa praticada com o objetivo de superar limitações dos amidos nativos e aumentar a utilidade deste polímero em aplicações industriais. O objetivo da pesquisa foi avaliar a aplicação de amidos de milho e mandioca modificados (fosfatação e oxidação) no processo de clarificação de cerveja artesanal, visando a obtenção de uma cerveja “limpa” e translúcida. Foram elaboradas oito cervejas testando os amidos aniônicos: amido de milho oxidado 1% (MiO 1%); amido de milho oxidado 2% (MiO 2%); amido de mandioca oxidado 1% (MaO 1%); amido de mandioca oxidado 2% (MaO 2%); amido de milho fosfatado baixo (MiFB); amido de milho fosfatado alto (MiFA); amido de mandioca fosfatado baixo (MaFB); amido de mandioca fosfatado alto (MaFA). Essas amostras foram comparadas com uma cerveja submetida ao mesmo processo utilizando o clarificante goma carragena (GCar) e com uma cerveja sem adição de clarificante (SC). As amostras foram submetidas às análises de compostos fenólicos, flavonóides, biureto, espectrofotometria, turbidez e viscosidade relativa para verificar a possível ação clarificante. Foi realizada a caracterização físico-química das amostras de cerveja artesanal (pH, extrato real, acidez, teor alcóolico, extrato primitivo e grau real de fermentação). A aplicação de amidos modificados reduziu o teor de compostos fenólicos, flavonóides, proteínas, e a viscosidade relativa no decorrer do processo. Além disso, a clarificação foi notada nas análises de turbidez e espectrofotometria. Pode-se concluir que alguns amidos destacaram-se, superando os resultados apresentados pela goma carragena na etapa final do processo. No entanto, notou-se que a eficiência destes amidos ocorre a partir da maturação, diferente da goma carragena que clarifica principalmente na etapa da fervura. Em um aspecto global, sugere-se que na fosfatação, a fonte botânica não influenciou, e as amostras destaques na clarificação foram o amido de milho fosfatado baixo (2,8%) (amostra 7), o amido e milho fosfatado alto (8,6%) (amostra 8) e o amido de mandioca fosfatado alto (amostra 10). Para a oxidação a amostra que apresentou melhor desempenho foi o amido de mandioca oxidado 1% (amostra 4).
The flavor of beer is determined by the feedstock, the type of process and the yeast used, in addition to the compounds produced during fermentation and maturation, that ecxercises greater impact. The production of modified starch is an alternative practiced with the aim of overcoming the limitations of the native starches and increase the usefulness of this polymer in industrial applications. The objective of the research was evaluate the application of corn and cassava modified starches (phosphatation and oxidation) in the craft beer clarification process to getting a beer "clean" and translucent. Were elaborated eight beers testing the anionic starches: oxidized corn starch 1% (MiO 1%); oxidized corn starch 2% (myo 2%); oxidized cassava starch 1% (MaO 1%); oxidized cassava starch 2% (MaO 2%); phosphate corn starch low (MiFB); phosphated corn starch high (MIFA); phosphated cassava starch low (MAFB); phosphate cassava starch high (MAFA). These samples were compared with a beer submitted to the same process using the clarifier carrageenan gum (CARG) and with a beer without added clarifier (SC). The samples were submitted to analysis of phenolic compounds, flavonoids, biuret, spectrophotometry, relative viscosity and turbidity to verify possible clarifier action. Was realized physicochemical characterization of craft beer samples (pH, real extract, acidity, alcohol content, original extract and real degree of fermentation). The application of modified starches reduced the content of phenolic compounds, flavonoids, proteins, and the relative viscosity during the process. In addition, the clarification was noted in turbidity analysis and spectrophotometry. It can be concluded that some starches stood out, overcoming the results presented by carrageenan gum in the final stage of the process. However, it was noted that the efficiency of these starches occurs from the maturation, different of carrageenan gumthat clarifies mainly in the boiling step. In a global aspect, it is suggested that in the phosphatation, the botanical source did not influence, and the highlight samples in clarification were phosphated corn starch low (2.8%) (sample 7), phosphated corn starch high (8 , 6%) (sample 8) phosphated cassava starch high (sample 10). To the Oxidation. the sample that showed better performance was oxidized cassava starch 1% (sample 4).

O mercado cervejeiro passa por uma revolução voltada à produção em escala artesanal ao invés de escala industrial, devido às expectativas dos consumidores em busca de alta qualidade e novo sabor do produto final. Visando produzir uma cerveja leve com relação ao teor de extrato e álcool, com sabor diferenciado, foram realizados vários ensaios de adição de gengibre no processo de produção. O mais viável resultado foi obtido com adição de 2g L-1 de lascas de gengibre in natura na maturação. A cerveja artesanal adicionada de gengibre foi produzida em escala laboratorial, para permitir sua análise físico-química e análise sensorial. Paralelamente, foram analisadas outras vinte e oito amostras de cerveja Pilsen para efeitos comparativos com relação aos aspectos físico-químicos. De acordo com o resultado do teste sensorial, o índice de aceitabilidade global foi de 92%, estando também acima de 70% o índice dos atributos individuais avaliados. A cerveja artesanal adicionada de gengibre apresentou características mais próximas às amostras de “Cerveja” ao invés das amostras “Puro Malte”, segundo classificação com relação ao teor de malte, por meio de análises quimiométricas (PCA e HCA). Essa discriminação entre os grupos foi devida aos teores de álcool, grau real de fermentação, grau aparente de fermentação, potássio, calorias e magnésio. O produto final apresentou como características principais um baixo teor alcoólico (3,40o GL), baixo valor energético (115,44 KJ 100 mL-1) e extrato reduzido (7,81º Plato). Apesar do amargor mais acentuado (21,55 B. U.), o índice de aceitabilidade para o amargor permaneceu acima de 70%, com flavor picante e aromático.
The brewing market undergoes a revolution directing to production on a homemade scale rather than an industrial scale, due to the expectations of consumers searching high quality and new flavor of the final product. In order to produce a light beer with respect to the extract and alcohol content and different flavor, several ginger addition tests were carried out in the production process. The most viable result was obtained with addition of 2 g L-1 of ginger flakes in natura at maturation. The artisanal brewed beer of ginger was produced in laboratory scale, to allow its physical-chemical analysis and sensorial analysis. In parallel, others twenty-eight samples of Pilsen beer were analyzed for comparative purposes in relation to physico-chemical aspects. According to the result of the sensorial test, the overall acceptability index was 92% as also as individual attributes evaluated were also above 70%. The artisanal beer added with ginger showed characteristics closer to the "Beer" samples than the "Pure malt" samples, according to classification in relation to the malt content, by means of chemometric analyzes (PCA and HCA). This discrimination between groups was due to alcohol, real degree of fermentation (RDF), apparent degree of fermentation (ADF), potassium, calories and magnesium. The final product had a low alcohol content (3.40 oGL), low energy (115.44 KJ 100 mL-1) and reduced extract (7.81 oPlato). Despite the more pronounced bitterness (21.55 B. U.), the acceptability index forbitterness remained above 70%, with spicy and aromatic flavor.

FundaÃÃo de Amparo à Pesquisa do Estado do CearÃ
Objetivou-se avaliar o uso das glicerinas mista e bruta na alimentaÃÃo de codornas de corte. Foram executados dois experimentos, sendo um de digestibilidade para determinar os valores energÃticos da glicerina vegetal bruta e da mista semipurificada. No segundo experimento avaliou-se o desempenho, caracterÃsticas da carcaÃa e da carne de codornas de corte recebendo diferentes nÃveis de inclusÃo dessas glicerinas nas dietas. No ensaio de digestibilidade utilizou-se 180 codornas de corte, dos 14 aos 21 de idade, alojadas em gaiolas para estudos metabÃlicos, distribuÃdas em delineamento inteiramente casualizado em esquema fatorial 2x2+1, sendo 2 nÃveis de substituiÃÃo da raÃÃo referÃncia pela glicerina (10 e 20%), dois tipos de glicerinas (vegetal e mista), mais a raÃÃo referÃncia, totalizando 5 tratamentos com 6 repetiÃÃes de 6 aves. O perÃodo experimental foi de oito dias, sendo quatro para a adaptaÃÃo e quatro para coleta total de excretas. A glicerina vegetal bruta apresentou maior energia metabolizÃvel aparente corrigida pelo balanÃo do nitrogÃnio com base na MS (EMAn kcal/kgMS), como na MN (EMAn kcal/kgMN), 5.195 e 4.759, contra 3.884 e 3.472 para a glicerina mista semipurificada, para os valores energÃticos, respectivamente. No segundo experimento utilizou-se 432 codornas de corte de 1 a 42 dias de idade, distribuÃdas em delineamento inteiramente casualizado em esquema fatorial 2x4+1, sendo 2 tipos de glicerinas (vegetal e mista), 4 nÃveis de inclusÃo de glicerinas nas dietas (5, 10, 15 e 20%), mais a raÃÃo controle, sem inclusÃo de glicerina, totalizando 9 tratamentos com 4 repetiÃÃes de 12 aves. Aos 42 dias as aves passaram por jejum sÃlido de oito horas, para o abate, sendo duas aves de cada repetiÃÃo separadas dentro do peso mÃdio, para posteriores anÃlises. Avaliou- se o consumo de raÃÃo, ganho de peso, conversÃo alimentar, rendimento de carcaÃa, de cortes (peito e coxa+sobrecoxa), teor de gordura abdominal, biometria dos ÃrgÃos (fÃgado, coraÃÃo e moela), amÃnia volÃtil, umidade e PH da cama, bem como as caracterÃsticas fÃsicas e sensoriais da carne. Os dados foram submetidos à anÃlise de variÃncia e os nÃveis de inclusÃo das glicerinas, foram desdobrados em polinÃmios. Para comparaÃÃo em relaÃÃo ao tratamento controle, foi utilizado o teste de Dunnett (5%). Observou-se diferenÃa para o desempenho, onde a glicerina mista proporcionou maiores resultados para consumo de raÃÃo em todos os perÃodos analisados, bem como na conversÃo alimentar de 1 a 21 dias e de 1 a 42 dias de idade das codornas. NÃo foi observada diferenÃa entre as glicerinas utilizadas para a amÃnia volÃtil, enquanto entre os nÃveis de inclusÃo das glicerinas houve efeito linear crescente para essa variÃvel à medida que se adicionou qualquer das glicerinas nas raÃÃes. O pH da cama foi superior ao se utilizar qualquer nÃvel de inclusÃo da glicerina vegetal quando comparado ao tratamento controle, bem como a partir de 10% de inclusÃo os valores de pH sÃo maiores ao se utilizar a glicerina vegetal e nÃo a mista. Nenhum dos fatores analisados interferiu no teor de umidade da cama. NÃo foram observadas diferenÃas para o rendimento, jà a gordura abdominal mostrou-se maior nas aves que consumiram raÃÃo contendo glicerina vegetal. Para as caracterÃsticas fÃsicas da carne considerou-se a perda de peso por cocÃÃo, forÃa de cisalhamento e capacidade de retenÃÃo de Ãgua, onde os dados para os nÃveis de inclusÃo das glicerinas foram desdobrados em polinÃmios, enquanto que para as glicerinas usado o Teste F. Jà para as caracterÃsticas sensoriais, aroma, cor, sabor e avaliaÃÃo global, as mÃdias foram comparadas pelo teste de Ducan a 5%. O uso de glicerina vegetal ou mista nÃo interferiu nas caracterÃsticas sensoriais da carne de codorna (P>0,05), podendo ser usada em atà 20% de inclusÃo nas raÃÃes. Para as caracterÃsticas fÃsicas houve diferenÃa (P<0,05) para forÃa e cisalhamento sendo os nÃveis 12,5% da GMS e 12,78% da GVB os que apesentaram melhores resultados. Para PPC e CRA nÃo houve diferenÃa (P> 0,05) entre os tratamentos analisados. Conclui-se que as duas glicerinas possuem potencial para serem utilizadas atà 20% na alimentaÃÃo de codornas, sem prejudicar o ganho de peso, o rendimento e a qualidade da cama, sendo a glicerina bruta a que apresenta maior quantidade de energia. No entanto, 13% de inclusÃo de glicerina nas raÃÃes de codorna proporciona uma carne mais suculenta.
The objective was to evaluate the use of mixed and gross glycerines on slaughter quail. Two experiments were performed, one of digestibility to determine the energy values of crude vegetable glycerin and semipurified mixed. The second experiment evaluated the performance, carcass characteristics and meat quail meat receiving different levels of inclusion in the diets of these glycerides. In the digestibility assay was used 180 quails, from 14 to 21 of age, housed in cages for metabolic studies, distributed in a completely randomized design in a factorial 2x2 + 1, 2 ration of replacement reference levels for glycerin (10 and 20%), two types of glycerides (crop and mixed), the more the reference diet, totaling five treatments with 6 replications of 6 birds. The experiment lasted eight days, four for adaptation and four for excreta collection. Gross vegetable glycerin had a higher apparent metabolizable energy corrected by nitrogen balance based on MS (AMEn kcal / kgMS) as the MN (AMEn kcal / kgMN), 5,195 and 4,759, against 3,884 and 3,472 for the semipurified mixed glycerin to the energy values, respectively. In the second experiment we used 432 quails 1- 42 days old, distributed in a completely randomized design in a factorial 2x4 + 1, 2 types of glycerides (vegetable and mixed), 4 glycerines inclusion levels in diets (5, 10, 15 and 20%) over control diet without the addition of glycerin, a total of 9 treatment with 4 replications of 12 birds. At 42 days the birds have undergone solid fasting for eight hours for slaughter, two birds of each separate repetition within the medium weight, for further analysis. It were evaluate the feed intake, weight gain, feed conversion, carcass yield, cuts (breast and thigh + drumstick), abdominal fat, biometry of the organs (liver, heart and gizzard), volatile ammonia, moisture and PH of the bed, as well as physical and sensory characteristics of meat. Data were subjected to analysis of variance and levels of inclusion of glycerides, they were deployed in polynomials. For comparison compared to the control treatment was performed using the Dunnett's test (5%). Difference was observed for performance, where the mixed glycerol provided greater results for feed intake in all periods analyzed, as well as feed conversion 1-21 days and 1-42 days of age of quail. No difference was observed between the glycerides used for volatile ammonia, while between the levels of inclusion of glycerines there was increasing linear effect for this variable as they added either glycerines in feed. The pH was superior to the bed using any inclusion level of vegetable glycerin compared to the control treatment and from 10% to include the pH values are higher when using the vegetable glycerine and not mixed. None of the analyzed factors interfered with the moisture content of the bed. There were no difference for yield, since abdominal fat was higher in birds fed diet containing vegetable glycerin. For the physical characteristics of the meat considered the weight loss for cooking, shear strength and water holding capacity, where data for inclusion levels of glycerides were deployed in polynomials, while for the glycerides used Test F . As for the sensory characteristics, aroma, color, flavor and overall evaluation, the means were compared by 5% Duncan test. The use of vegetable glycerin mixed or no effect on the sensory characteristics of quail meat (P>0.05), can be used in up to 20% inclusion in diets. For the physical difference (P <0.05) for strength and shear levels being 12.5% of GMS and 12.78% of GVB apesentaram that the best results. CRA for PPC and there was no difference (P> 0.05) between treatments analyzed. It follows that the two glycerides have potential to be used up to 20% in the feed quail, without harming the weight gain, the yield and quality of the bed, and the crude glycerin presents the highest amount of energy. However, 13% inclusion of glycerin in quail rations provides a more succulent meat.

Fingerprint profiles generated through GC analysis, are powerful tools for quality control in the food and beverage industry. Beer aroma profiles can be used for the fingerprinting of specific beer brands or for trouble shooting purposes such as the identification of off-flavours. The multichannel silicone rubber trap (MCT) lends itself perfectly to this task. The simplicity and robustness of the MCT makes it ideal for concentrating the volatile compounds that constitute the aroma of an alcoholic beverage such as beer. The retention of these substances by the silicone is based on dissolution into the polymer. This gives more intrinsic stability to the concentrated aroma compounds than traditionally used, adsorption based methods, so transport of the trap and contents should not be a problem. Thermal desorption is used to introduce the trapped aroma compounds to the chromatographic instrument. This eliminates the need for high purity solvents and greatly reduces the sample preparation time. The easily identifiable and stable background peaks from the silicone matrix makes the MCT ideal for repeated use with a thermal desorber. During this study the performance of the MCT as concentration device was investigated for its ability to concentrate aroma volatiles representing a wide range of volatilities. The sampling and desorption procedures were optimised in order to attain the required detection levels and repeatability of the analytical method based on this purge-and-trap sampling scheme
Dissertation (MSc (Chemistry))--University of Pretoria, 2007.
Chemistry
MSc
unrestricted

During fermentation, the yeast Saccharomyces cerevisiae produces a broad range of aroma-active esters that are important for the desirable complex flavour of beer. The sensory threshold levels of these esters in beer are low, ranging from 0.2 ppm for isoamyl acetate to 15-20 ppm for ethyl acetate. Although esters are only present in trace amounts in beer, they are extremely important as minor changes in their concentration may have dramatic effects on beer flavour. Therefore, optimization of the concentrations of these aroma-active esters in beer is of interest in beer brewing. The number and concentration of esters in beer may be influenced by the fermentation parameters, nutritional composition of fermentation medium and yeast strain type. Therefore, this study investigated the influence of fermentation temperature, pH, and wort nutritional supplements (amino acids and zinc) on the production of yeast-derived ester compounds. In addition, the overall fermentation performance was evaluated based on the reducing sugar and Free Amino Nitrogen (FAN) utilization, ethanol production and yeast cell density. These parameters were analysed using the Dinitrosalicyclic acid method, Ninhydrin assay, Gas Chromatography and standard spread plate technique. The concentration and stability of ethyl acetate, isoamyl acetate, phenyl ethyl acetate, ethyl hexanoate, ethyl decanoate and ethyl octanoate was monitored during storage at 4 °C and room temperature (RT), in the final beer by Chromatography. The expression levels of the ester synthetase genes under conditions that resulted in the highest increase in ester production were quantified by Real-Time PCR. For the lager beer, the best fermentation performance was achieved at RT (±22.5°C), resulting in the utilization of the highest amount of nutrients and production of 4.86% (v/v) ethanol. This was accompanied by the highest production of acetate and ethyl esters, which were 40.86% and 87.21%, respectively, higher than that of the control. Spent yeast density ranged from 2.492 to 3.358 mg/ml for all parameters tested, with the highest yield produced when wort was supplemented with 0.120 g/l zinc sulphate. Fermentations at 14 °C yielded the highest foam head stability and spent yeast viability with a foam head rating of 2.67 and a spent yeast viability of 3.85 × 107 cfu/ml. Ester compounds were relatively stable at 4 °C than at room temperature decreasing by only 7.93% after three months. Of all the volatile esters produced, ethyl decanoate was the least stable, with a 36.77% decrease in concentration at room temperature. For the ale beer, the best fermentation performance which resulted in the highest nutrient utilization was achieved when wort was supplemented with 0.75 g/l L-leucine resulting in the utilization of the highest amount of nutrients (51.25% FAN and 69.11% reducing sugar utilization) and production of 5.12% (v/v) ethanol. At the optimum fermentation pH of 5, 38.27% reducing sugars and 35.28% FAN were utilized, resulting in 4.32% ethanol (v/v) production. Wort supplemented with 0.12 g/l zinc sulphate resulted in 5.01% ethanol (v/v) production and 54.32% reducing sugar utilization. Spent yeast density ranged from 1.985 to 2.848 mg/ml for all parameters tested with the highest yield produced when wort was supplemented with 0.120 g/l zinc sulphate. This was also accompanied by the highest yeast viability of 2.12 × 107 cfu/ml achieved on day 3 of fermentation. Supplementation with 0.75 g/l L-leucine yielded the highest foam head stability with a rating of 2.67. Overall, ester compounds were relatively more stable at 4 °C than at RT decreasing by only 6.93% after three months, compared to a decrease of up to 16.90% observed at RT at the same time. Of all the volatile esters produced, ethyl octanoate was the least stable, with a 32.47% decrease in concentration at RT, phenyl ethyl acetate was the most stable ester at RT, decreasing by 9.82% after three months. Wort supplemented with 0.75 g/l L-leucine resulted in an increase in isoamyl acetate and phenyl ethyl acetate production by 38.69% and 30.40%, respectively, with a corresponding high expression of alcohol acetyltransferases, ATF2 (133.49-fold higher expression than the control). Elevation of fermentation temperature to RT resulted in the upregulation of ATF2 (27.11-fold), and producing a higher concentration of isoamyl acetate. These findings indicate that ester synthesis during fermentation is linked to both substrate availability and the regulation of gene expression. Therefore, it would be possible to manipulate the expression of certain ester synthestase genes to create new yeast strains with desirable ester production characteristics. Results from this study also suggest that supplementing wort with essential nutrients required for yeast growth and optimizing the fermentation conditions could be effective in controlling aroma-active ester concentrations to a desired level in beer.
Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.

Dissertação de mestrado integrado em Engenharia Biológica (área de especialização em Tecnologia Química e Alimentar)
As cervejas são classificadas em numerosos estilos consoante as distintas características organoléticas que apresentam. Este facto sugere que, a nível gastronómico, diferentes cervejas possam harmonizar de forma ideal com diferentes alimentos. A teoria de food pairing é um método científico que permite definir as melhores combinações entre alimentos com base no seu perfil aromático. De acordo com esta teoria, dois alimentos combinam bem juntos se partilharem, entre si, aromas-chave. Assim, no âmbito desta dissertação, propôs-se desenvolver e validar metodologias de harmonização que permitissem obter as melhores combinações para cada cerveja artesanal Sovina, baseadas nos princípios de food pairing e considerando as características de flavour específicas de cada cerveja. Numa primeira fase foi efetuada uma análise por GC-MS às seis cervejas regulares Sovina de forma a identificar os respetivos perfis de compostos voláteis e, desse modo, permitir distinguir as cervejas entre si. A análise de diferenças entre cervejas foi realizada por análise de componentes principais (PCA). Numa segunda fase, foram desenvolvidas metodologias baseadas em duas abordagens de harmonização distintas: partilha de compostos voláteis (M1) ou partilha de descritores de aroma totais ou de relevo (M2.1 e M2.2). Uma pré-validação destas metodologias passou pela análise de correlação (Pearson) dos resultados com os obtidos pelo software foodpairing® e por comparação com dados de preferência de consumidores. A análise PCA permitiu distinguir as várias cervejas, sugerindo, contudo, que as cervejas Helles, Bock e Amber são as mais semelhantes entre si. Relativamente às metodologias de harmonização, M1 apresentou correlação positiva fraca, sem significado estatístico com o foodpairing®, ao passo que, para M2.1 e M2.2 a correlação foi negativa fraca, sem significado estatístico. Por sua vez, os dados de preferência de consumidores por pares cerveja-alimento com a cerveja Helles, demonstraram ser consistentes com os resultados obtidos pela metodologia M1, parecendo relacionar-se positivamente com estes. Os resultados obtidos neste trabalho demonstram a complexidade associada ao estudo do flavour e não permitem validar as metodologias de acordo com o método foodpairing®, apresentando fracas correlações com o mesmo. A comparação com a preferência de consumidores, por outro lado, sugere o potencial sucesso da metodologia M1, demonstrando a necessidade de ser realizada, futuramente, uma validação mais robusta desta metodologia.
Beers can be classified in many styles, depending on the different organoleptic characteristics they present. This suggests that, at the gastronomic level, different beer styles may pair with some foods better than with others. The food pairing theory is a scientific method that proposes the definition of the best pairings between foods based on their aromatic profiles. According to this theory, foods pair well together if they share, with each other, aromas that are relevant. Therefore, the main aim of this work was to develop and validate methodologies of harmonization that can produce the best food pairings for Sovina craft beers, considering the principles of food pairing and the specific flavour characteristics of each beer. First, a chromatographic analysis of the six Sovina beers was performed by GC-MS, in order to identify the volatile profile of each bear. The analysis of these results allows to differentiate the beers through a principal component analysis (PCA). Then, methodologies of pairing beer and foods were conceived based on two distinctive approaches: sharing volatile compounds (M1) or sharing aroma descriptors – total (M2.1) or relevant (M2.2). A pre-validation of these methodologies was done by correlating (with Pearson correlation coefficient) the results obtained in this work with those from the company foodpairing®, and by comparing the results with data on consumer’s preference. PCA analysis allowed to distinguish the beers, being Helles, Bock and Amber, the most similar. Regarding the pairing methodologies, M1 presented a positive, but weak correlation, with no statistical significance with foodpairing® method. The correlation between foodpairing® method with M2.1 and M2.2 was negative and weak, thus also with no statistical significance. Data on consumer’s preference for Helles and food pairs, on their turn, were consistent with M1 results, suggesting to be positively related to them. The results of this work show the complexity associated with the study of flavour in foods and do not allow to validate the methodologies according to the foodpairing® method, presenting weak correlations. The comparison with consumer’s preference data, on the other hand, suggests the potential success of the M1 methodology, demonstrating the need for a more robust validation of this methodology in the future.

In this thesis the optical changes of beers and model beer solutions during their photodegradation were studied. The optical changes - change of absorbance - were measured on the prototype of apparatus COLORTURB and were correlated with sensory tested intensity of the lightstruck flavour of beer and with riboflavin content in samples. High correlation between the lightstruck flavour intensity, the loss of absorbance at the wavelength of 450 nm and the riboflavin content loss was found. The partial recovery of the absorbance for both beers and model beer solutions was found and was attributed to the riboflavin photoproducts transformation. Powered by TCPDF (www.tcpdf.org)

碩士
國立中興大學
生物科技學研究所
107
Craft beer is manufactured by traditional brewing methods with four ingredients water, malt, hops and yeast. From those simple ingredients, thousands of various types of beer can be created. Basically, the fermentation can be divided into two main types with different yeast species, the top fermentation using Saccharomyces cerevisiae (ale) and the bottom fermentation using S. pastorianus (lager). Yeast is the most critical factor to determine the flavor of craft beer during fermentation. Therefore, beer brewing using different strain of yeast can result in different flavor. Even using the same strain of yeast in brewing with different pitching rate can also result in different flavor. Although the brewing history has been recorded for thousands of years, there is not much scientific report on this issue. Therefore, the aim of this study is focusing on the difference of the aroma produced by brewing with different yeast strains and with different pitching rates. I used three different commercial wheat beer yeast strains Hefeweizen, Bavarian Hefeweizen, and Bavarian Weizen in this study. Each of the yeast strain was single colony isolated; genomic DNA was extracted; specific DNA fragment was PCR amplified; and the amplified DNA was sequenced. The sequence of each strain was compared with the database in NCBI. The results revealed that Hefeweizen is S. cerevisiae and Weizen is S. bayanus. I then used the plate count method to calculate the yeast viable rate and used it to determine the pitching rate for the fermentation experiments. The results indicated that lower pitching rate could slow down the speed of fermentation. The major compounds of fermenting aroma analyzed by GC-MS are isoamyl acetate, ethyl hexoate, ethyl octanoate, phenethyl acetate, phenylethyl alcohol, and 4-vinyl guaiacol. After comparison of the aroma compound intensity from different wheat beer, Hefeweizen has little difference in aroma at different pitching rates. Bavarian Hefeweizen had a slight difference in the compounds phenylethyl alcohol, phenethyl acetate and 4-decenoic acid ethyl ester at different pitching rates. Most of the compounds in higher pitching rate of Bavarian Weizen were higher than those from low pitching rates.

Staling in beer is inevitable. Oxidation and increased temperatures are the main causes of stale flavors in bottled beers. Since 1934, research has been done to identify compounds and pathways involved in creating stale flavors. Although many research papers report stale flavors, there is not a lexicon per se of stale aromas for North American lagers. This study has been divided into two parts, 1) the process of developing a lexicon for stale aromas for North American lagers and its application, and 2) the use of a consumer panel to determine whether the North American lager consumer has a preference for aged versus fresh beer and whether the consumer could perceive a difference between the two. In the first study, three brands of North American lagers were aged in 27°C storage for three months and 38°C storage for two weeks. A lexicon for staling aroma for North American lagers was created, using a trained descriptive panel. The lexicon had two tiers; the first tier had five descriptors that were category headings for the second tier of descriptors. Panelists were instructed to rate the first tier descriptors, but using the descriptors in the second tier was optional. To validate the lexicon, descriptive analysis was performed on the stored samples. The data were analyzed using principal components analysis (PCA) for the first tier descriptors and generalized procrustes analysis (GPA) for the second tier descriptors. The lexicon was used successfully, characterizing the control beers as sulfury and fruity and the aged beers as sweet brown. Within the sulfury category, panelists described control beers with the attributes perm solution and skunky. Within the sweet brown category, panelists described the aged beers with the descriptors baked pineapple and honey. The beers stored at different storage temperatures behaved differently across time. The maps constructed with PCA and GPA show a tendency for control samples to start out sulfury and, through time, age with sweet brown characteristics. In the second study, a consumer panel was implemented to 1) determine if the average North American lager consumer had a preference for fresh versus stored beer, and 2) to determine if perceivable differences existed between the fresh versus stored samples. A consumer test was designed using the three North American lagers that were tested in the trained panel. The target number of consumers for each brand was 100. The aged beer was stored at 38°C for 1 and 2 weeks, and the control was stored at 1°C for that time period. A preference test, followed by a triangle test, was performed on control versus 1 week at 38°C and control versus 2 week at 38°C for each brand (2 preference and 2 triangle tests for each brand; control versus 1 week and control versus 2 weeks). The results showed no significant preference for any brand/time point. Brand A had the only significant difference (p <0.05) between samples stored at 38°C for 2 weeks and the control (The results showed no preference). Additional research must be done for more conclusive information, but this research shows that a small group of North American lager consumers do not have a preference between aged beer and fresh beer and, for the most part, cannot tell a difference between aged beer and fresh beer.
Graduation date: 2002

Malt, wort and beer samples representing a single pilot brew were extracted from Celite columns with Freon 114. Total extracts were analyzed by gas chromatography/mass spectrometry. Compounds were identified that were unique or common to beer, wort or malt and quantities present were determined for those common to the three sample types. Concentrated extracts were separated by liquid chromatography on partially deactivated silica gel packed in Teflon tubes, using Freon 11 as the solvent. Fractions from liquid chromatography were analyzed by descriptive sensory evaluation. Those fractions selected as bearing cereal-like, grassy, nutty or malty aroma characteristics were analyzed by gas chromatography. Freon extracts and fractions were found suitable for descriptive sensory evaluation and this was used to advantage in locating fractions with the desired aroma characteristics. Cereal-like, grassy, nutty or malty aroma characters were associated with liquid chromatographic fractions containing primarily alcohols, aldehydes and ketones. The Ascending Method of Limits for determination of the threshold of added substances in beer was critically reviewed and a new threshold test was developed. The new test design reduces the sample requirement from eighteen to twelve for each session. In contrast to the Ascending Method of Limits, the new test design was amenable to statistical evaluation and statement of a level of confidence for the threshold intervals determined. Both a nine-point intensity scale of difference from the labeled reference and a category scale were applied to the new test design. Intensity scale data were normalized and subjected to analysis of variance and a series of one-sided t-tests to determine individual and combined panel threshold intervals. Category scale data were analyzed by a rank sums test to determine individual thresholds and the R-index values thus obtained were subjected to analysis of variance and orthogonal contrasts of means to establish the combined panel threshold. The intensity scale method applied to the new test design provided the lowest and narrowest estimates of the threshold interval in comparative testing with the category scale method and the Ascending Method of Limits and, in addition, required fewer replications than the category scale method to establish the threshold interval.
Graduation date: 1989

碩士
國立宜蘭大學
食品科學系碩士班
102
It is well-known that meat flavour is thermally derived through the Maillard reaction. Many desirable meat flavor volatiles are synthesized by heating water-soluble precursors such as amino acids and carbohydrates. There have been various types of simulated meat flavours recombined through flavor components isolated from cooked meat products prepared from hydrolyzed yeast and enzymatically hydrolyzed beef. The purpose of this study was to find out the best combination of amino acids, sugars, hydrolyzed yeast and hydrolyzed beef. Using descriptive sensory analysis and gas chromatography–mass spectrometry (GC/MS) analysis to investigate changes in aroma characteristics of beef-like process flavours. The results showed that the volatile compounds of process flavour, contained 17 aldehydes, 2 alcohols, 2 ketones, 1 thiazole, 12 furans, 3 thiophenes and 1 dimethyl trisulfide. The result of sensory analysis confirmed that the processed flavor of leucine (L) 0.40g and lysine (L) 0.6g was strong in beefy, meaty and meat-related characteristics and had high correlation with the following compounds: 3-methylthiophene, and 4-methyl-5-thiazoleethanol in sample. Therefore the amount of leucine and lysine would be fix in 0.4 g and 0.6 g to go on the next experiment. The result of sensory analysis confirmed that the sample with cysteine (0.45 g) with thiamine (0.6 g) had high correlation with overall liking and beef odor liking. Presumably due to cysteine (Cys) 0.45 g and thiamine (THI) 0.6 g had high correlation with the following compounds: 2-methyl-3-furanthiol, 4-methyl-5-thiazoleethanol and unknown8 in sample. As the result, the component of sulfur compounds would decide to be cysteine 0.45 g and thiamine 0.6 g to go on the next experiment. The result of sensory analysis confirmed that the processed flavor of beef hydrolysate 61.08 g and yeast hydrolysate 20.36 g were strong in beefy, meaty and meat-related characteristics and had high correlation with the following compounds: n-dodecanal, 4-hexen-3-one, tetrahydro-2-furanmethanol, thiophenecarboxaldehyde and benzaldehyde in sample. The final result showed that cysteine (0.45 g), thiamine (0.6g), taurine (0.5g), glucose (1g), xylose (1g), tallow (10 g), leucine (0.4 g), lysine (0.6 g), Angel yeast powder (4 g) with beef hydrolysate 61.08 g and yeast hydrolysate 20.36 g are the best combination to mimic beef odor.

In an effort to increase beef demand, the beef industry has expanded beyond commodity beef merchandizing into value-added cuts. As these beef cuts are developed it is critical that the industry be able to characterize the flavor attributes of these products. A trained sensory panel is typically utilized to determine flavor characteristics of food products including beef. Prior to product evaluation, a product lexicon or dictionary of terms is developed in order to anchor and orient panelists to the various samples. Once the lexicon is developed, it can be used by a descriptive panel to evaluate samples. Currently, the beef industry does not have a full beef flavor lexicon with defined references; therefore a comprehensive sensory lexicon for describing the aroma and flavor of beef was developed by a 6-member panel at Kansas State University with extensive experience in lexicon development and descriptive analysis. Three descriptive panels utilized the beef flavor lexicon developed in Phase I by Kansas State University to evaluate the effect of USDA Quality Grade and cut on beef flavor and to validate the beef flavor lexicon to determine if it is ready for use by scientists. iv Results indicated that Choice steaks and roasts were higher in fat-like, and overall sweet flavor. Eye of round roasts were lowest in aroma and flavor attributes and bottom round roasts were highest in liver-like flavor. Flat iron steaks were highest in fat-like flavor compared to other cuts and top loin steaks tended to have the lowest intensity in flavor attributes compared to the steak cuts. The three sensory panels rated steaks and roasts similarly for aroma and flavor attributes and were generally less than 2- to 1-point different in rating intensities. The beef flavor lexicon was easily applied across the three institutions and should be ready to be used as a viable research and product development tool.

This work set out to examine the methodologies of dry hopping, compare different hop materials, and look at the extraction behavior of different types of hop compounds. This work consists of two discrete studies, where the first study informed the design of the second. The first study measured the concentrations of hop aroma compounds extracted from Cascade hops during dry hopping using a model beer system devoid of malt, yeast aromas, and hops. Cascade hops pelletized by four different processors yielded different particle size distributions and pellet densities. These pellets were dosed into a degassed medium (water, 6% v/v ethanol, pH 4.2) and the hop aroma extraction was measured periodically over a one week period. Solid phase micro-extraction (SPME) followed by gas chromatography (GC-FID) was used to analyze the levels of aroma compounds in the extraction medium. Variation in the hop pellet physical properties did not significantly impact the extraction rate of hop volatiles such as linalool, geraniol, limonene and myrcene with one exception. One treatment showed an increased absolute concentration of geraniol. Separately, dry hop aroma extraction was measured over a short time (1 day) at room temperature in an unhopped beer using small-scale (1L), stirred vessels. Irrespective of the hop form (whole or pellet), the concentrations of hydrocarbon terpenes peaked between 3 and 6 hours and subsequently declined, while the concentrations of terpene alcohols continued to increase throughout the 24 hour dry hop extraction. The rate of hop aroma extraction did not appear to be significantly influenced by hop pellet properties and occurred rather rapidly regardless of the hop form. The second study examined the extraction of hop aroma compounds during a pilot brewery scale (~4hL) dry hop treatment. Dry hop treatments consisted of whole cone hops and pellet hops (Cascade cultivar, 2011 harvest) which were dosed into cylindroconical vessels which were either stirred with a pump or left quiescent. Samples were taken for GC-FID and HPLC analysis as well as sensory evaluation at various time points between 30 minutes and 12 days. Polyphenol and alpha acid extraction was highest in a stirred system dosed with pellets. Hop aroma compound extraction was also the highest in the stirred system utilizing pellet hops. The sensory panel rated the stirred pellet samples as having the highest hop aroma, bitterness, and astringency. The results showed that hop flavor from dry hopping can be readily achieved with much shorter contact time than the current 4-12 day industry practice.
Graduation date: 2013

碩士
國立澎湖科技大學
觀光休閒系碩士在職專班
104
The purpose of this study is to explore the effects of the brand awareness, brand image, brand spokesman and perceived risk on the purchase intention. The questionnaire survey was conducted over 381 interviewees (the consumers of the fruit flavor beers) in Taipei, Taichung and Kaohsiung through purposive sampling. The data were analyzed by descriptive analysis, item analysis, reliability analysis, confirmatory factory analysis and structure equation modeling with SPSS and LISREL. Through SEM analysis, the research result shows: The brand awareness has no direct effect on the purchase intention. However, the brand awareness has positive effect on the purchase intention through the perceived risk indirectly. The brand image has the positive effect on the purchase intention. The brand spokesman has the positive effect on the purchase intention. The brand awareness has the negative effect on the perceived risk. The brand image doesn’t have the significant effect on the perceived risk, and has no negative effect on the perceived risk. The brand spokesman has the positive effect on the perceived risk, and has no negative effect on the perceived risk. The perceived risk has the negative effect on the purchase intention.

We hypothesized that carcass subcutaneous fat location would affect sensory and quality traits. Five carcass fat sources were tested: brisket, chuck, plate, flank, and round. Ground beef was formulated using each fat source and extra-lean beef trim (>95% lean) to contain 80% lean trim and 20% fat trim. Patties (100 g) were evaluated for color, lipid oxidation, fatty acid composition and consumer evaluation. Flavor was analyzed using a Gas chromatography with mass spectrometry (GC/MS) on the headspace above a cooked (74 degrees C) patty in a heated (60 degrees C) 473 mL glass jar with a solid phase micro-extraction (SPME) fiber. Color, thiobarbituric acid reactive substance assay (TBARS), consumer sensory, and cook/freezer loss data showed no differences (P > 0.05) among carcass locations. Percentage stearic acid was lower (P = 0.044) in the brisket than in the chuck and flank. The brisket was higher in percentage cis-vaccenic acid (P = 0.016) and in the saturated fatty acid to monounsaturated fatty acid ratio (P = 0.018), and lower (P = 0.004) in the percentage of total saturated fatty acids than all other sources of subcutaneous fat. Butanedione was highest (P = 0.013) in the flank and plate fat. Brisket tended to be higher (P = 0.054) than flank, plate, and round in 1-octen-3-ol. Brisket was higher (P = 0.008) than chuck, flank, and round, but not different (P > 0.05) than plate in octanedione. Brisket was higher (P = 0.003) than all other sources for beefy aroma. Flank was higher (P = 0.047) than chuck and round for chemical aroma. Brisket was higher (P = 0.004) than all other sources except flank for floral aromas. Plate was higher (P = 0.029) than all other sources for heated oil aromas. For secondary aroma descriptor, round was higher (P < 0.001) than flank, plate, and chuck for dairy. While differences in some key fatty acids and aromatics existed among carcass locations, when the fat was diluted with a common lean source, fat source did not have a negative effect on sensory or quality traits. Therefore, formulating ground beef using subcutaneous fat from specific locations on a carcass may improve the beef aromatics without negatively affecting sensory or quality traits.

Hops (Humulus lupulus L.) are primarily used to provide specific characteristics to beer, such as bitterness, aroma, flavor, and microbial stability. The chemical composition of hops, relative to how they are used during the brewing process, dictates the expression of these characteristics. Of the raw ingredients that go into making beer, hops are perhaps the most costly. Considerable resources are required to grow quality hops, and therefore, brewers and hop growers alike have a common goal of obtaining the highest quality hops possible. However, quality can be a relative term. While it is commonly agreed upon that high brewing values, such as α-acids and essential oil content, and robust structural integrity are indicators of quality hops, there are many opinions of the ideal aroma. Changes in the chemical composition of hops during plant maturation are a dynamic process requiring a comprehensive, in-depth chemical and sensory analysis in order to maximize the characteristics of interest to brewers. The complex aroma chemistry associated with hops in beer has been a confounding variable for the practical brewer, and a deeper understanding of hop aroma development during cultivation is needed. The effect of harvest date, location, and cultivar on key chemical components of Willamette and Cascade hops was investigated for the 2010 and 2011 growing seasons. Hops were harvested at 3 time points (Early, Typical, and Late), within a 3-week interval from 2 different farms in the Willamette Valley, Oregon. A split-plot experimental design for each cultivar was used; each farm represented a main plot and harvest years were designated as subplots. American Society of Brewing Chemist standard methods of analysis were used to measure moisture content, hop acids and their homologs, Hop Storage Index, total essential oil content and volatile profile by GC-FID. Additionally, difference testing, descriptive analysis, and consumer acceptance testing was conducted using beers brewed with either Typical or Late harvested Cascade hops from the 2010 harvest year. The response of analytes was dependent on the cultivar being examined, its location within the Willamette Valley, as well as days until harvest. Hop acids did not change appreciably during plant maturation for the period examined, while hop oil content increased hyperbolically to a plateau as the hops aged on the bine. Increases in oil quantity were strongly correlated (r > 0.90) with increases in α-pinene, β-pinene, myrcene, limonene, methyl heptanoate, and linalool concentrations. For Cascade, α-pinene, β-pinene, myrcene, limonene, ρ-cymene, caryophyllene, E, β-farnesene, and humulene all increased from Early to Typical points but no increase was observed between the Typical and Late time point. Linalool and methyl heptanoate increased between each time point while citral and humulene epoxide differed between Early harvest and Late harvest, but not between Early and Typical or Late and Typical harvests. For Willamette hops, α-pinene, β-pinene, myrcene, limonene, ρ-cymene, and linalool all increased between each time point. Caryophyllene, E β-farnesene, humulene, farnesol and citral all increased from Early harvest to Typical harvest but no difference was observed between Typical and Late. Clear sensory differences were found between beers brewed with Typical harvest Cascade hops and Late harvest Cascade hops, in terms of difference testing, descriptive analysis and consumer preference tests.
Graduation date: 2013

碩士
國立高雄應用科技大學
觀光與餐旅管理系
102
The 2012 Council of Agriculture, Executive Yuan data pointed out that Taiwan's beef consumption per person per year is around 3 to 4 kg. This makes the overall market scale for Taiwan was 92,000,000 kg (202,400,000 lb), valued at US$382,536,000 per year. More than 90 percent of these beef are imported, mainly from the USA, Canada, New Zealand and Australia and other countries. However, American beef imports in recent years were fluctuate due to safety concerns of mad cow disease and Ractopamine residue. The purpose of this study was to explored Taiwan consumers’ Perceptions on nutrition, safety, taste, and flavor of US beef and their intention to purchase US beef after a national debate on the safety of Ractopamine residual. A national Survey was conducted in 2010-2011 on 600 consumers. Five hundred and thirty usable survey were analyzed. The results showed that nutrition awareness, safety perception, taste and flavor are positively correlated to purchase intentions. Nutrition cognition, safety perception, taste, and flavors all have a significant effect on US beef purchase intention.

Dissertação de mestrado integrado em Engenharia Biológica (área de especialização em Tecnologia Química e Alimentar)
Beer is a beverage obtained by alcoholic fermentation, containing alcohol, extract and carbon dioxide. It is prepared from barley malt, hops, brewing water, and yeasts (from which derive the predominant influences on overall beer types). Since different beer styles result from the combination and relationships between several factors (ingredients, processing, packaging, marketing and culture), the final flavor will be different. However, the beer flavor is not static but in a continuous changing state. The point where maturation ends and deterioration begins is undoubtedly different for different beers and probably different for each consumer. The aim of this study was to investigate the changes that occur during the storage/ageing of six different of beers: four craft (Weiss, Pilsner, Stout, Red Ale) and two commercial beers (Weiss and Pilsner). The main differences between these beers are the fact that craft beers are made exclusively of natural raw material, no preservatives or additives are added and are they are not pasteurized or filtered (containing the yeast in the bottle). The beers were analyzed sensory and chemically (major and minor compounds) once a month over six months. Minor compounds were analyzed for the first and sixth month. Craft beers showed an aromatic profile much more intense than the commercial beers and kept the profile constant over the six months (as the commercial beers). The results allowed to conclude that the craft beers maintain the quality of a commercial beer, over six months, with the benefit of having most intense flavors and aromas. Through the analysis of major compounds, no clear trends for ethanol and sugars concentrations were obtained. The concentration of organic acids on craft beers was higher than the concentrations typically found in commercial beers. The results of minor compounds analysis were in line with the aromatic profiles obtained by sensory analysis, as well as those portrayed in the literature. The results showed that most of the principal aging markers reported were not found in the beers studied. However other compounds were found like higher alcohols, ketones and acids. The validation of the method of extraction of minor compounds (used to analysis by gas chromatography–mass spectrometry) was conducted. To validate the method several parameters were studied: linearity, sensitivity, detection and quantification limits, precision (repeatability and intermediate precision), matrix effect, time effect and accuracy (spiking test). The results showed that the method satisfies the specifications determined for each validation parameter. This means that the validation of the extraction method was a success.
A cerveja é uma bebida obtida por fermentação alcoólica que contem álcool, extrato e dióxido de carbono. É preparada a partir de malte de cereais, lúpulo, água e leveduras (a partir dos quais derivam as influências predominantes dos diferentes tipos de cerveja). Uma vez que os diferentes tipos de cervejas resultam da combinação e relação entre vários fatores (ingredientes, processamento, embalagem, marketing, cultura) o aroma final será diferente para cada uma delas. No entanto, o aroma não é estático mas em estado constante de mudança. O ponto em que a maturação acaba e a deterioração começa é sem dúvida diferente para diferentes cervejas e provavelmente diferente para cada consumidor. O objetivo deste trabalho foi estudar as alterações que ocorrem durante o armazenamento/envelhecimento de seis cervejas diferentes: quatro artesanais (Weiss, Pilsner, Stout, Red Ale) e duas comerciais (Weiss e Pilsner). As principais diferenças entre estas cervejas é o facto de as artesanais serem feitas exclusivamente a partir de matéria-prima natural, não serem adicionados aditivos nem conservantes e não ser pasteurizada nem filtrada (contendo a levedura na garrafa). As cervejas foram analisadas sensorial e quimicamente (compostos maioritários e minoritários) uma vez por mês ao longo de seis meses. Os compostos minoritários foram analisados no primeiro e no último mês. As cervejas artesanais mostraram um perfil aromático muito mais intenso do que as comerciais e mantiveram o perfil constante ao longo dos seis meses de armazenamento (assim como as comerciais). Os resultados permitiram concluir que as cervejas artesanais mantêm a qualidade de uma cerveja comercial, ao longo de seis meses, com a vantagem de terem os sabores e aromas mais intensos. A análise dos compostos maioritários não permitiram determinar tendências claras acerca da concentração de etanol e de açúcares. As concentrações de ácidos orgânicos mostraram ser mais elevadas do que as concentrações tipicamente encontradas nas cervejas comerciais. Os resultados da análise dos compostos minoritários vão de encontro aos perfis aromáticos obtidos pela análise sensorial assim como os retratados na literatura. Estes resultados mostraram que a maioria dos principais marcadores de maturação reportados não foram encontrados nas cervejas, no entanto outros compostos foram encontrados tas como álcoois superiores, cetonas e ácidos. Foi realizada a validação do método de extração de compostos minoritários, utilizado para a análise por Cromatografia Gasosa- Espectrometria de Massa. De forma a validar o método foram estudados vários parâmetros: linearidade, sensibilidade, limites de deteção e quantificação, precisão (precisão intermédia e repetibilidade), efeito matriz e efeito do tempo e exatidão (teste de recuperação). Os resultados mostraram que o método satisfaz as especificações determinadas para cada parâmetro de validação, o que significa que a validação do método de extração foi um sucesso.

The effect of micronization (at 130 and 150 °C) as a potential heat treatment to reduce ‘beany’ aroma and flavor of cooked chickpea (Cicer arietinum) and green lentil (Lens culinaris) flours was investigated. A simultaneous distillation solvent extraction method was developed to extract key volatile compounds with potential contribution to ‘beany’ aroma and flavor notes in micronized pulse flours and analyzed by gas chromatography-mass spectrometry. Concentrations of volatile compounds such as pentanol, hexanal, 2-hexenal, hexanol, heptanal, furan-2-pentyl, 2-octenal, nonanal, 2,4 decadienal, and 2,4- undecadienal were significantly (P<0.05) decreased with micronization. Low fat burgers fortified with 6% micronized chickpea and green lentil flours showed significantly higher acceptability for aroma, flavor, texture, color and overall acceptability (p<0.05) compared to non-micronized samples in a consumer acceptability test with 101 consumers. In addition, fatty acid analysis of burgers showed burgers containing micronized pulses had higher level of linoleic and linolenic acid content.